Per-Encounter Powers

[pemerton]

Wow, that was a well thought-out and reasoned response to my umpteen million posts on this topic.

Thanks.

In general, though, I still feel that using encounter-based resources over daily-based resources really forces your hand as a DM. You have to craft every single encounter to be both challenging and interesting, and it can wear on you.

Agreed, but for me it's a bit like saying that an alarm clock forces your hand. It's a type of discipline and reminder. And because the other parts of the game all point the same way (more-or-less, at least), I don't find it a hard discipline to respond to. I haven't had the burnout experience you're describing - actually, the opposite. I had been GMing Rolemaster in a more-or-less encounter-based fashion. RM has a similar gonzo-fantasy vibe to D&D (especially at higher levels), but doesn't have the same mechanical tools and features to strongly support encounter-based play. So I have found the move to 4e very liberating and supportive of the approach I was trying to take anyway.

It also forces you as DM to use more artificial-feeling methods to control pacing to prevent that sort of problem.

I haven't found this - I find that the mechanics themselves generate the right dynamic - but I'm probably using the mechanics in a particular way (especially a lot of "say yes" stuff to skip over thematically unimportant exploration).

It also puts a damper on exploration or sandbox style play because each encounter has to be balanced.

<snip>

In Pathfinder, I've found that I was able to design adventures both in an encounter-based sense and in an exploration/sandbox sense. I specifically tested out this theory with this week's session, designing an adventure for the session that I could easily turn into a 4e adventure just by playing "swap the monsters". It worked beautifully.

<snip>

I want a system that's flexible enough to give me both options.

About 18 months ago I did a reverse experiment - used 4e to run an exploration-oriented scenario. The actual play report is here. I thought it went pretty well, but it was quite a bit different, I think, from how the same scenario would run in classic D&D.

I don't hate 4e and I don't hate encounter-based design. But I've already got 4e as a great system for that style of gameplay. I don't want Next to reinvent the wheel or try to fix something that's not really broken. I want it to give me more options as a DM for what stories and adventures I can cover in my games, not less.

I don't have a strong view on what D&Dnext should be. I do know that if it is weaker in its support for encounter-based play than 4e, I probably won't be running it. But I may not be running it in any event, as once our 4e campaign comes to an end I'm hoping my players will be happy for me to run some Burning Wheel.

I do have strong views on what D&Dnext should be if it is to satisfy its stated design goals, though! Which include making the 4e experience possible - so they will have to think about how spell durations, resource recovery rates, etc all factor into encounter based play - and which also include the "3 pillars" - so they will have to think about how you set meaningful stakes for non-combat interaction, and how to dynamically resolve those sorts of situations. The playtest tends to make me a little pessimistic about where they're heading in both the respects.

 

[pemerton]

Firstly, an excellent and informative post!

Thanks.

But the swinginess they are "fixing" is undone by more powerful daily powers and action points (or the lack thereof).

I haven't played mid-to-high level 3E, but compared to Rolemaster or classic D&D 4e doesn't have nova-ing. The players of high level wizards in RM would make it a point of pride to maximise the amount of spell points they could spend in a single round! Classic D&D doesn't go quite that far, but you can spend all your best spells in a single combat and then have none less.

Daily powers in 4e are important, but - at least in my experience - not quite that important. Hence the reduction in swinginess.

The bottom line is that such things are game mechanics. However, it is nice when these mechanics are given a little bit of tweaking to represent something about the campaign world.

Encounter powers tell me something about the campaign world too. For example, in my game the fighter's and ranger's encounter powers tell me that they are masters of the halberd and the greatbow respectively.

It's a different sort of "something", but it's not nothing.

I would prefer a little more flexibility here.

I'm a little on the hardcore side here (probably similar in outlook to [MENTION=27160]Balesir[/MENTION]). I think "flexibility" is hard to achieve, and tend to prefer reasonably focused design where all the pieces are pushing the same way.

The playtest document, for example, has a 1 hour duration combat buff (Crusader's Strike). From the point of view of [-]exploration[/-]encounter-based play that's a nightmare, because instead of pushing the focus of play and engagement into the situation at hand, it pushes it towards timekeeping - and either GM fiat of this, or pedantic tracking of the amount of time required for every exploratory action the players declare for their PCs in the course of transition between encounters.

Luke Crane, in the Burning Wheel Magic Burner (p 259), has some interesting stuff to say about durations:

In the Burning Wheel core rules, I talk about time [ie spell durations] in terms of actions [= a heartbeat, about a second or so], minutes, hours, days, months and years. Makes sense, no? That's how time passes, right? True, but game time is very different than real time. What's important in real time is not the same as what's important in game time.

Game time is factored in chunks of tests, conflicts, scenes, sessions, adventures and campaigns. . . I favour these new durations, rather than the traditional time durations. Why? Because these durations are much easier to manage as an in-game resource than real time. Burning Wheel doesn't have very good time management rules, but it has excellent game resource management rules . . .

What's an hour in the game? How much adventuring can you accomplish in an hour? How many tests? How many Duels of Wits? At best it's an arbitrary determination made by the GM. There are no rules for it. . . Sometimes that's cool, but other times, we need another set of limits to help us define magical effects.​

Now I would say that classic D&D did have time management rules - "the turn" as a unit of exploratory action, a rest and wandering monster cycle defined in terms of turns, etc. I'll leave it to others to judge whether or not these were excellent rules. My view is that they are clearly rules that push away from rather than towards encounter-based play.

But once you drop them - say, in the spirit of "flexibility" (and I don't think the playtest had these sorts of rules) - then you end up with these durations that become subject to arbitrary GM determination. And that also pushes strongly away from encounter-based play, because the whole point of encounter-based play is that the GM frames the scenes but the players get to decide which player resources to bring to bear, and how. Whereas hour-long buffs encourage the players to haggle over the scene-framing ("Come on, all that stuff we did didn't take an hour, did it?") rather than to engage the scene itself.

I think this is probably one thing that some people have in mind when they say that the playtest reminds them of 3E - it lacks the exploration rules of classic D&D. (Did 2nd ed have those rules? If not, then a comparison to 2nd ed might be just as apt.)

 

[Herremann the Wise]

Thanks.

I haven't played mid-to-high level 3E, but compared to Rolemaster or classic D&D 4e doesn't have nova-ing. The players of high level wizards in RM would make it a point of pride to maximise the amount of spell points they could spend in a single round! Classic D&D doesn't go quite that far, but you can spend all your best spells in a single combat and then have none less.

Daily powers in 4e are important, but - at least in my experience - not quite that important. Hence the reduction in swinginess.

Personally, I attribute the comparative reduction in swinginess in 4e more to other factors such as less differentiation between defenses (compared to 3e saves) as well as funnelling almost everything through hit point attrition rather than having a variety of different glass jaws and an overall increase in hit points (which monster vault/MM3 addressed to put a little more zing into combat). However, my point was that whenever we play 4e, the difference between encounters where characters are full (dailies and everyone has an action point) and when they are pretty much just on encounter powers and below is quite different in terms of "swinginess".

Encounter powers tell me something about the campaign world too. For example, in my game the fighter's and ranger's encounter powers tell me that they are masters of the halberd and the greatbow respectively.

It's a different sort of "something", but it's not nothing.

4e power fluff really does not work for our group (it's a little too wahoo/over the top for our group's conservative types). As such its the keywords that really define things for us and so yes, there certainly isn't nothing but (and please understand this is really only my personal opinion) such keywords really epitomise for me the mechanics first, fluff second approach that I feel 4e emphasized. It is a little harder to connect such things to the campaign world when the fluff that should be doing this doesn't. [Where my obvious preference is for fluff first that the mechanics grow from; much less elegant with great holes left in the various permutations of design space but heh...]

I'm a little on the hardcore side here (probably similar in outlook to [MENTION=27160]Balesir[/MENTION]). I think "flexibility" is hard to achieve, and tend to prefer reasonably focused design where all the pieces are pushing the same way.

The playtest document, for example, has a 1 hour duration combat buff (Crusader's Strike). From the point of view of exploration-based play that's a nightmare, because instead of pushing the focus of play and engagement into the situation at hand, it pushes it towards timekeeping - and either GM fiat of this, or pedantic tracking of the amount of time required for every exploratory action the players declare for their PCs in the course of transition between encounters.

Luke Crane, in the Burning Wheel Magic Burner (p 259), has some interesting stuff to say about durations:

In the Burning Wheel core rules, I talk about time [ie spell durations] in terms of actions [= a heartbeat, about a second or so], minutes, hours, days, months and years. Makes sense, no? That's how time passes, right? True, but game time is very different than real time. What's important in real time is not the same as what's important in game time.

Game time is factored in chunks of tests, conflicts, scenes, sessions, adventures and campaigns. . . I favour these new durations, rather than the traditional time durations. Why? Because these durations are much easier to manage as an in-game resource than real time. Burning Wheel doesn't have very good time management rules, but it has excellent game resource management rules . . .

What's an hour in the game? How much adventuring can you accomplish in an hour? How many tests? How many Duels of Wits? At best it's an arbitrary determination made by the GM. There are no rules for it. . . Sometimes that's cool, but other times, we need another set of limits to help us define magical effects.​

Now I would say that classic D&D did have time management rules - "the turn" as a unit of exploratory action, a rest and wandering monster cycle defined in terms of turns, etc. I'll leave it to others to judge whether or not these were excellent rules. My view is that they are clearly rules that push away from rather than towards encounter-based play.

But once you drop them - say, in the spirit of "flexibility" (and I don't think the playtest had these sorts of rules) - then you end up with these durations that become subject to arbitrary GM determination. And that also pushes strongly away from encounter-based play, because the whole point of encounter-based play is that the GM frames the scenes but the players get to decide which player resources to bring to bear, and how. Whereas hour-long buffs encourage the players to haggle over the scene-framing ("Come on, all that stuff we did didn't take an hour, did it?") rather than to engage the scene itself.

I think this is probably one thing that some people have in mind when they say that the playtest reminds them of 3E - it lacks the exploration rules of classic D&D. (Did 2nd ed have those rules? If not, then a comparison to 2nd ed might be just as apt.)

I love this type of discussion and information that gets at the heart of things so well done again.

What I think you are getting at is not "how long should an effect last?" but "when should an effect end". In this respect, an instantaneous effect is most likely the easiest duration to manage as it gives a single window of opportunity for characters to react/interrupt, the effect happens and then the effect no longer needs to be tracked. Compare this to an effect that ends at the end of your next turn or one that lasts for x number of rounds and you have something that needs to be carefully tracked. Too many of these at the table in the one encounter and you have a whole stack of effort expended in trying to ensure these more finicky durations are being carefully tracked. We use an initiative tracker which is somewhat helpful for the latter x rounds but useless for the former end-of-next-turns. As such, both these durations are ones I'd prefer to see abandoned.

Now just as you mention the awkwardness of the one hour duration, the encounter duration while better can still produce situations such as your example upthread where a power that lasts until the end of the encounter is taken advantage of by continuing to go on. However this stretches my "believability". Perhaps when I DM 4e, I have a comparatively stricter definition of encounter duration (if the players choose to continue on without an opponent the encounter should end).

However with this stricter defining, I find that an "encounter" works much better as a unit of duration than a limiter of action. Just as I would prefer that range is more abstractly described as either close, standard or long (where close is within 30', standard is somewhere on a conventional battlemat, and long is anywhere within visual range) I would rather see duration as a more abstract instantaneous, concentration, encounter, day(s)/week(s)/month(s)/year(s) etc., semi-permanent (contingent upon a specific trigger not occuring), and permanent (cannot be undone). These are all duration-finishing triggers that are easy to manage (with encounter being potentially the most contentious duration but also perhaps the most common).

Anyway, good discussion again - you deserve more XP that hopefully a few extra people can provide.

Best Regards
Herremann the Wise

 

[pemerton]

4e power fluff really does not work for our group (it's a little too wahoo/over the top for our group's conservative types). As such its the keywords that really define things for us and so yes, there certainly isn't nothing but (and please understand this is really only my personal opinion) such keywords really epitomise for me the mechanics first, fluff second approach that I feel 4e emphasized. It is a little harder to connect such things to the campaign world when the fluff that should be doing this doesn't.

I agree that the keywords are hugely important (and I tend to ignore the italicised flavour unless I'm very confused about what's going on, and I actively loathe the bloated Essentials fluff). I think the rulebooks are really weak on this, because the only place in which keywords are discussed as anchors between mechanics and fiction is in the DMG discussing damage to objects. The main discussion in the PHB and the Rules Compendium is all about mechanics-to-mechanics interaction rather than mechanics-to-world interaction.

To try and explain further: the PHB tells met that [fire] keyword powers interact with [fire] keyword feats and other enhancers. But only in the damage-to-objects discussion do they make explicit that [fire] keyword powers mean that the effect is fiery,a nd so will set comubstibles on fire. In the case of a Deathlock Wight, it is the [fear] keyword that tells us that its push effect from Horrific Visage is the victim recoiling in horror.

So I don't see it as mechanics first, fluff second because I think the fiction is built into the mechanics via the keywords. And if the rulebooks had been clearer about this, I think a lot of the rather arid debates about whether a power can do cold damage without having the cold subtype, etc, would quickly have gone away. Another example of this is the sorcerer at-will Blazing Starfall. It has both [fire] and [radiant] keywords, but it only deals fire damage if cast by a cosmic sorcerer (it sets up a fire zone). The sorcerer PC in my group is a chaos sorcerer, and so his blazing starfall does no fire damage. To me that makes it obvious that the power has no [fire] keyword, and I have ruled it that way from the get go. I think technically that is a house rule, but I think if the role keywords play in mediating mechanics and fiction were better explained, my ruling would be a consequence of rules-as-written.

just as you mention the awkwardness of the one hour duration, the encounter duration while better can still produce situations such as your example upthread where a power that lasts until the end of the encounter is taken advantage of by continuing to go on.

Agreed. But 5 minutes is (in my view) much easier to adjudicate than 1 hour, just because of the reduced complexity of things to track, the lesser distances that can be travelled, etc. Also, because of the way that healing surge expenditure and encounter power recovery and encounter duration effects are integrated, it is to a significant extent self-balancing: it doesn't matter if, on this occasion, I let the players get away with packing a bit too much, or a bit to little, into their 5 minutes, because while they get to keep their buff they don't get their powers or their hit points back. Conversely, suppose I tell the players, "Sorry, 5 minutes have passed - you've lost your buff" well they can at least rest and get their powers and hp back, and perhaps an action point as well.

The problem with the 1 hour buff is that it's on a cycle with no countervailing pressures - for the player it's strictly a purge to have the GM call the hour over. My Rolemaster game used to be full of this stuff - 1 min/lvl and 10 min/lvl durations. I'm really glad to be rid of them.

Your preferred suite of durations strikes me as much less harmful: instantaneous corresponds roughly to Luke Crane's "test"; encounter to his "conflict" or "scene"; days/weeks to his "session" or "adventure"; months/years to his "campaign". But I would be surprised if the mainstream anti-encounter power D&D players would sign onto these durations. I think there is a lot of support for reintroducing the fiddly durations that I hate.

 

[Balesir]

Luke Crane, in the Burning Wheel Magic Burner (p 259), has some interesting stuff to say about durations:

In the Burning Wheel core rules, I talk about time [ie spell durations] in terms of actions [= a heartbeat, about a second or so], minutes, hours, days, months and years. Makes sense, no? That's how time passes, right? True, but game time is very different than real time. What's important in real time is not the same as what's important in game time.

Game time is factored in chunks of tests, conflicts, scenes, sessions, adventures and campaigns. . . I favour these new durations, rather than the traditional time durations. Why? Because these durations are much easier to manage as an in-game resource than real time. Burning Wheel doesn't have very good time management rules, but it has excellent game resource management rules . . .

What's an hour in the game? How much adventuring can you accomplish in an hour? How many tests? How many Duels of Wits? At best it's an arbitrary determination made by the GM. There are no rules for it. . . Sometimes that's cool, but other times, we need another set of limits to help us define magical effects.​

Ah, thanks for posting this!

I have only got as far as reading the core BW rules, and this was something that bothered me. It's nice to see that Luke has (later) come to the same conclusion I have - that game-world time durations are often just a cipher for "arbitrarily, at GM whim, the effect will end". Nowadays I much prefer durations (as well as other mechanics) that are linked exclusively to the game, rather than to the game world. If the game world time is to be the measure of duration, I would rather make systems that measure out that time. In the same way that science is tending to postulate that time is merely the measure of physical change, game time seems to me to logically be the measure of game (mechanical) changes, so that, without such changes, it cannot pass.

 

[pemerton]

Ah, thanks for posting this!

No worries. I'm always happy to post a good designer quote!

It's nice to see that Luke has (later) come to the same conclusion I have - that game-world time durations are often just a cipher for "arbitrarily, at GM whim, the effect will end". Nowadays I much prefer durations (as well as other mechanics) that are linked exclusively to the game, rather than to the game world.

In the same section, Luke does explain that ingame "real" times work for some parts of BW. It works for recovery (of resources and from wounds) and for practice, because these are on the same "downtime" cycle (and so there's a type of trade off going on). And it also works for Fight and Range and Cover, because it is used to adjudicate what can be done in a single action or exchange.

It's the inbetween space - in D&D terms, the space between "rounds" and "encounters", on the one hand, and "downtime" on the other - where adventuring takes place but not in a continuous time-delimiting fashion, that "real" times become GM fiat.

(As I said upthread, I think classic D&D did have mechanical management of that in-between time - namely, the turn. But for me the turn - with its wandering monster checks, and searching at doors and for traps, etc - is a symbol of everything I can't stand about classic D&D.)

 

[Balesir]

In the same section, Luke does explain that ingame "real" times work for some parts of BW. It works for recovery (of resources and from wounds) and for practice, because these are on the same "downtime" cycle (and so there's a type of trade off going on).

Yes - this is the 4e "extended rest", in effect, which I wish had been de-coupled "officially" from the diurnal cycle, because it doesn't always fit there very well (e.g. you can't have tense, week-long chases or searches where there is no time to fully recover resources - tinkering with the "extended rest" mechanics a bit can sort this out really easily).

But, I think this is just a case of "game world time" and "mechanical system time" being congruous; basically, there has been one "tick" of the game - call it an "episode", or something - that has completed, thus triggering the resource renewal. That this "tick" happens (notionally) to correspond with a set, game-world time interval is actually incidental, in my view.

And it also works for Fight and Range and Cover, because it is used to adjudicate what can be done in a single action or exchange.

And this is a classic case of just what I was trying to explain, above, too. A "combat round" is, in the system, "the quantity of game required for your character to perform a prescribed aliquot of actions". It's a bit like saying "a second corresponds to a set number of oscillations between specified states in caesium-133 atoms at zero degrees kelvin"; when the caesium has changed state that many times, you know a second has passed. When every creature has taken (or declined to take) its quota of actions, you know a combat round has passed.

I actually like (from a general verisimilitude point of view) the approach that HârnMaster and the De Bellis Antiquitatis wargame rules (among others, I'm sure, but these two I happen to know) take, here. They just say that a "game round/turn" is "approximately X amount of game time", while actually defining the turn as "however long it takes in the game world for the actions that happen in the round to happen". In HM, if you want to know roughly how much time a combat took, take the number of combat rounds and multiply by 10 seconds - but be aware that this does not mean that each actual round took exactly ten seconds! Some will take more, some less. Since nobody in the game world is even remotely likely to have a timepiece capable of measuring minutes accurately, let alone seconds, this is vanishingly unlikely to matter one jot.

(As I said upthread, I think classic D&D did have mechanical management of that in-between time - namely, the turn. But for me the turn - with its wandering monster checks, and searching at doors and for traps, etc - is a symbol of everything I can't stand about classic D&D.)

Yeah, the problem - with most such "systems", actually, not just D&D - is that it defines only the time aliquot and a movement rate. Borderline OK if all the characters do is move, but totally useless otherwise. The "rules" then amount (at best) to the GM taking a wild-assed guess at how much time various actions take. I have been involved in learning exercises where we planned and executed "get over the canyon with these bits of wood and this rope" type stuff, so I know just how wildly inaccurate both my and other people's estimates of the time taken to do such stuff is. As a "system", frankly, just rolling 3d10 for the number of minutes taken to do anything would be an infinitely better bet.

Better still, for durations, I would use:

1) Instataneous. Easy.
2) Applies to next roll/check/attack (if this could be later - e.g. in another character's turn, give out a token of some sort that can be "spent" for the bonus, to make remembering/tracking trivial).
3) Applies until some condition or remedy is applied; could be simply ending your turn, successfully making a saving throw (always taken at the end of your turn), triggered by a specific action (by the character with the condition or another) or something more esoteric. Basic rule - no counting. Next time the trigger happens, the effect ends.
4) Appies until no longer sustained. This is almost like the previous one; there is a trigger that ends the effect unless a specific action is taken to sustain it past the trigger.
5) Applies until the end of the encounter (this is actually just a special case of 3, with "an encounter ends" or "a short rest is taken" as the condition).
6) Applies for ever.

4e almost got this right - but the clustercockup of "start of target's next turn"/"end of target's next turn"/"start of initiator's next turn"/"end of initiator's next turn" blows the whole gaff, sadly.

 

[pemerton]

you can't have tense, week-long chases or searches where there is no time to fully recover resources - tinkering with the "extended rest" mechanics a bit can sort this out really easily

My group uses the day as the default extended rest measure, but in the chase/search situation I use skill challenges to regulate access to extended rests. It's not perfect, but it's workable within the parameters of the system as written.

A "combat round" is, in the system, "the quantity of game required for your character to perform a prescribed aliquot of actions".

Luke, in the Magic Burner, is also envisioning using the real-world time measure of a round to adjudicate what can be done (ie common-sense intuitions about "how many heartbeats would that take to do?").

The "rules" then amount (at best) to the GM taking a wild-assed guess at how much time various actions take.

Probably not an unfair description - and the more intricate the activity, and the larger the unit of time it's being slotted into, the more wild-assed it becomes, I think!

Yeah, the problem - with most such "systems", actually, not just D&D - is that it defines only the time aliquot and a movement rate. Borderline OK if all the characters do is move, but totally useless otherwise.

Classic D&D also has rules for searching which interact with the time rules. Movement + searching - what else would a game need?

 

[Abstruse]

I haven't found this - I find that the mechanics themselves generate the right dynamic - but I'm probably using the mechanics in a particular way (especially a lot of "say yes" stuff to skip over thematically unimportant exploration).

I'm a big "go with it" improv-style DM myself. I've scared players before when I walk into a session and they think I'm completely unprepared because I just have a list of NPC/monster stats and maybe a map or maybe not to run a session. Never had a boring session though except the time when the players spend 2+ hours going over with the wizard what they'd have him craft during downtime in the kuo-toa temple. I can do the same thing in 4e, but I have to do more planning.

When I say the difference between encounter-based design and adventure-based design is the difference between an action movie and an adventure movie comes really from where you're spending your time during DM prep. In 4e, I spent all my time creating interesting encounters, finding just the right monsters with just the right mix of powers and just the right terrain. In PF, I spend all my time creating the monsters themselves, taking the core race and putting class levels on them and putting gear on them and so on...makes me think more about what the NPC's history and theme and backstory and personality.

So the encounter-based design of 4e makes me focus more on how the action will play out, which makes the encounters themselves stand out. Adventure-based design makes me think more of the story and history of the characters, which puts them at the forefront. Again, neither approach is bad and you can put time in for the other side of the equation in both systems, but the system pushes you to do it in how it's designed in each case.

What I really want in Next as a DM is flexibility. I want to be able to run pretty much any style of game myself and my players want to run. I want to be able to do Keep on the Borderlands, Tomb or Horrors, The Evil Eye, Against the Giants, Storm Tower, and Dragonlance all in the same system with very little fuss and muss when it comes to the rules. I want to be able to just flip through my archive of Dungeon Magazines or my box of old modules and adventures, pick one at random whether it's from 1981 or 2011 and be able to run it by just replacing monster stats and still have it make sense.

I also want to eat ice cream for dinner every night and not be fat. I don't expect to get exactly that, but the closer they get, the happier I'll be.

 

[Neonchameleon]

I'm a big "go with it" improv-style DM myself. I've scared players before when I walk into a session and they think I'm completely unprepared because I just have a list of NPC/monster stats and maybe a map or maybe not to run a session. Never had a boring session though except the time when the players spend 2+ hours going over with the wizard what they'd have him craft during downtime in the kuo-toa temple. I can do the same thing in 4e, but I have to do more planning.

When I say the difference between encounter-based design and adventure-based design is the difference between an action movie and an adventure movie comes really from where you're spending your time during DM prep. In 4e, I spent all my time creating interesting encounters, finding just the right monsters with just the right mix of powers and just the right terrain. In PF, I spend all my time creating the monsters themselves, taking the core race and putting class levels on them and putting gear on them and so on...makes me think more about what the NPC's history and theme and backstory and personality.

When I run 4e I do extremely little mechanical prep for non-capstone combat encounters*. There's a secret to running a good encounter on the fly. You need one interesting/interactive terrain feature and a hook.

The interesting terrain feature is normally something to push the monsters (or the PCs) in/on/over/off but may as easily be a sniper tower that makes a magnificent vantage point or a bunker with arrowslits - something to encourage movement and give the PCs better options than just "I hit him".

The hook is something that's going to impact the fight. It may be a motivation (trying to assassinate someone - he's trying to escape and hide behind his guards). It may be an escalator (reinforcements arriving/the building catching on fire (with the fire being the interactive terrain feature). It may be a condition (there must be no survivors works - as does making sure either a specific monster dies or even that a specific monster survives). The hook as often as not can come from the players and their plans.

As for monster balance, I just grab a handful that fit together thematically and should be there of at least two types most of the time (counting standard brutes and soldiers as a single type in most cases and minions as a single type). Any two of (brutes/soldiers), skirmishers**, artillery, and lurkers ganging up are going to make for interesting tactics (just artillery and lurkers is brutal) and a controller should make the fight interesting even with just one other type.

And with the 4e monster manuals being as useful as they are, I can do all this at the table literally in a matter of seconds. (On a couple of occasions I didn't have the hook until I'd started drawing out the map).

What prep I do is therefore story and worldbuilding. Or I just run on the fly with an already existing world (we currently have alternating DMs with my group so if one of us is unwell the other can step in).

* A capstone encounter would be a major boss fight or trying to stop an army. I prepare those quite seriously of course.

** Skirmishers IME come in two types - "vanilla skirmishers" who just do medium damage at range and in melee and "advantage skirmishers" who do low damage without CA (or some other condition) and high with it. Vanilla skirmisher + brute or vanilla skirmisher + soldier doesn't make much of a fight.