Can anyone give me some basic DM monster tactical tips? I feel like I'm not particularly challenging my party (although they don't seem to be too bored or otherwise unhappy). In tonight's game of three encounters I managed to bloody a PC maybe three times total.
The 2nd level knight has an armor class of 24, and in one encounter my monster had to roll an minimum of 18 in order to hit him. But if he tries to disengage he gets whacked.
I saw somewhere else in this thread that he has +2 armor. There are item guidelines that need to be followed if you want to keep the balance. Personally I use inherent bonuses so the issue takes care of itself. In any event, PCs shouldn't really expect their first magic armor until 4th-level (if you use the inherent system, that's when they get their equivalent) and in either case, shouldn't be getting +2 armor until 6th-level at minimum. However, with +1 armor, his AC would be only one point lower.
I would suggest using lots of controllers or artillery that target defenses other than AC. Note that plenty of other monsters might have an attack that doesn't target AC as well, such as a brute that has a multi-hit "swinging weapon" power that targets Reflex.
I always use encounters of at least +1. Even an easy encounter will simply use a few slightly higher-level NPCs. (It's mainly because some of my PCs have high defenses. Alas, their offense is often a point short, so it's a bit of a knife edge there.)
I have a PC in my group who has a really high AC too, despite using the point buy rules, as his character is a halfling rogue who pumped everything into Dex, getting his AC and attack bonuses a point or two above what they "should" be. His Will and Fortitude defenses are quite weak however, since he can't boost his other stats much at all. He also tends to drop a lot when exposed to damage-dealing auras, even when the opponent isn't deliberately singling him out for damage.
Meanwhile, the thief has an attack bonus of +11 even without combat advantage, which he gets 80% of the time due to tactical trick, flanking, or the mage's spells.
I don't know what to say to that kind of bonus. That sounds a bit high for 2nd-level. Check their math, and check you're handing out proper magic items.
In my limited DMing experience the best way to challenge the party is to use a "party" of monsters, as in only one or two of each monster type. For instance, IME, the rogue keeps "ganking" spellcasters, especially templars (I'm running Dark Sun). So one trick is to put a soldier next to the templar. Many soldiers have an ability that gives them a free attack against an enemy who targets anyone other than themself, and often these attacks are debilitating (they don't just deal damage, they might also knock the opponent prone, immobilize them, restrain them, inflict a -2 penalty to attack rolls, etc). Note that soldiers also mark PCs (even that knight), drawing aggro away from squishy controllers.
In one encounter I forgot to do this, and used something like four controllers/artillery and only two soldiers. Needless to say the rogue got his pick of which squishy to target (anyone not standing next to a tough guy) and did massive damage.
Sad because in the previous encounter I did
not make that mistake, and despite an equivalent XP budget the battle had ended up being much more satisfying for both the players and myself. (It hadn't been a hard battle either.)
I guess I'm whittling their healing surges away as they heal after each encounter, but I don't feel like I'm ever really pushing them anywhere near the brink during the combats. These are Level+0 or +1 encounters. Maybe I need to bump up the encounter level? Use higher-level monsters which will have a better shot to hit?
That'll help to some extent, but you need to set up "combos". For instance, in a previous encounter, I used a controller monster with a special ability to inflict the "dazed" condition as a recharge power (the attack was versus Will, IIRC), along with skirmishers that had combat advantage and a soldier to protect it. Even if they couldn't flank, the skirmishers would often deal bonus damage to dazed opponents anyway. (And combat advantage helps a lot when the PCs have high AC.)
I can do this easily as I design new monsters in a really short period of time (a complicated one takes me half an hour at most) and I won't shy away from designing an entire themed group of monsters designed to fill all those roles and be backed up with combos. After all, my PCs don't shy away from using powers like this combo: use a pull power to pull a controller or artillery away from its allies right into the midst of the heavy melee characters, then watch them get killed in only one round.
One tactic I guess I will start trying is to bog down the knight with minions and let the tougher monsters attack the thief and mage. But that only lasts a couple rounds until he cleaves his way through the minions.
If the knight is doing his job right, he should be sticking next to the mage, killing anyone who hits them, or pushing them back, etc. (I'm more familiar with the fighter than the knight, but I know the knight can still "draw aggro" to himself.) So I don't see that as a good strategy, actually.
So my suggestions go like this:
1) Check your PC's math and don't hand out overpowered magic items. (I'm not even sure if a PC of 5th-level or less gets more than a +1 bonus from a +2 item.)
2) Use slightly higher-level monsters (regardless of encounter level equivalent). So a 2nd-level encounter might consist of 3 or 4 3rd-level monsters rather than 5 2nd-level monsters. Higher-level minions can let you dish out a stream of continuous damage, especially if they're artillery, which means they are less likely to be immediately killed.
3) Use the DMG2/MM3/Monster Vault damage expressions. Buy those books, especially the DMG2 and Monster Vault. (The MM3, unfortunately, focuses mainly on high-level monsters.) Update monsters that deal low damage in your Monster Builder (I don't have that, so I use index cards), and also use these expressions when designing your own monsters.
4) Assemble encounters to use different monster types. This might mean you need to design your own monsters, or buy monster books, etc. Some monster types, such as gnolls and hobgoblins, have a very wide variety of "types"; there are gnoll brutes, soldiers, controllers, artillery, skirmishers and leaders all around the 5th to 6th-level mark. (Note that you can "level down" or "level up" monsters using the DMG2 rules, so it's no problem if the monsters you want to use are too high level.) And feel free to blatantly steal monster abilities when designing your own, or "reskin" monsters with minor changes. (For instance, as a Dark Sun DM I can't use gnolls as there aren't any on Athas, but I can certainly take away their Pack Frenzy ability (their signature ability which the players would recognize) and replace it with something else that's nasty, then call them something else. The players won't realize they're effectively fighting gnolls.)
You should always have a soldier or two to protect your "squishy" spellcasting or ranged monster. You should always have monsters that attack a stat other than AC (or do damage automatically) - which your controller monster is likely to do. And pick skirmishers with useful abilities, especially the kinds that can potentially get past the knight and cut the PC mage or cleric to pieces. (Useful: anything with "Mobile Melee Attack" and a high movement speed.) Or use artillery instead of skirmishers.
5) Set up encounters so monster abilities synergize nicely, just like your PCs do all the time. A monster that can knock a PC prone works quite well with a monster that deals extra damage against foes that grant combat advantage. A monster that grabs PCs works well with a monster that has an aura which deals damage (especially if the "grabber" is immune to the aura for whatever reason).