D&D 5E Rules for adjusting CR on the fly?

[Fion]

Because the DMG isn't out yet I was just wondering if anyone had come up with rules for on-the-fly adjusting of CR for monsters? My group is on the small side (3 players) and we want to play one of the published adventures like HotDQ, but they are both designed for 4-6 players and are generally considered very hard even for a large group. I'm generally pretty solid about adjusting monster numbers to make combat a little easier or changing things up to add options that make a fight a little more suitable, but I wanted a way to adjust monsters as I needed.

Thankfully monster stats in DDN are on the whole very simple, so I'm sure someone has come up with a way to adjust them to tune CR up or down slightly. At least I hope.

 

[jrowland]

First, you shouldn't be adjusting CR at all, really. CR is a gauge of monsters "power". Ogres are CR2 due their "power" (ie hP, DPR, etc) if you adjust CR you are adjusting its HP, its DPR, its to hit modifier etc...in short, it stops being an Ogre (maybe ogre child, or Sick ogre) but then you are changing the narrative in the module. You can fudge it a bit (lower/raise to hit by 1 or 2, damage by 2-4, hp by some percent etc) and be ok, but there are too many moving parts to judge well to really come up with a new CR. As a rule of thumb -1 on attacks, -2 on damage and about 75% HP are probably good for a small party but...encounter difficulty is a function of "effective" XP budget, and multiple monsters are LARGE driving force in that determination. Smaller groups are key for smaller parties

Second, in a published adventure you are likely not going to see a CR > Party Level except in extreme/specific circumstances. So any creature presented should be "viable" for a smaller group as presented.

So, the best way to adjust encounter difficulty is reduce the number of monsters and/or number of encounters.

For HotDQ, I'd drop number of monsters in half. If you roll on a table and get 1d6 Kobolds, make it 1-3. If a set encounter has 6 kobolds and 4 cultists, make it 3 and 2, etc. I'd also use the average damage listed rather than roll. Random is spikey, and in a small party 2 random high damage rolls can drop 2/3 of your party, where in a larger party more than 1 guy is still standing. Average will help you pace as well. As DM you can see if your average damage means any hit kills a PC. If so, you might switch to more robust targets, or start having creatures run, or reinforcements arrive, etc.

In my own home run HotDQ, Im a using Average Damage -2 at 1st level, Average -1 when they hit 2nd, Average at 3rd, then Rolling from then on at 4th+. They are still getting their butts kicked at 1st level and after 2 sessions, are rolling backup characters, lol! We'll see. (4 PCs)

In the encounters session HotDQ I am running, I have 7 players. Since many are new to D&D, New to the system, Or very young, I won't increase number of creatures and I still think I'll use Average Damage -2 at 1st level, Average -1 when they hit 2nd, Average at 3rd, then rolling from then on at 4th+. I may change my mind if the first 2 or 3 encounters go too well for them.

Have fun and Good Luck!

 

[Fion]

Might be better for me just to prep and 'encounters' doc with adjusted xp budgets or replace a few enemies with thematically similar ones (CR 8 green dragon with a CR 6 White Dragon, etc). Wouldn't take that much more time, especially since the material would cut down my prep time significantly anyway.

Thanks for the tips on random encounters and static damage. That'll help too.

 

[Tony Vargas]

Playing with encounter difficulty on the fly is a little tricky because the number of enemies impacts the challenge in two ways. Obviously, there's the exp that each monster contributes, but, if you add or subtract enough monsters, there's also a multiplier that's affected, /and/ the size of the party also has a bearing on that multiplier.

So this isn't like 3e where you have a clear idea that 1 monster of CR=party level is meant to be a valid challenge, or 4e where you could adjust for missing or extra players by adding/subtracting the same number of standard monsters. It requires a little extra calculation, or just plain a better 'feel' for the challenge.

A simple rule of thumb is to change the number of monsters to match missing or extra players, or maintain the same ratio. For instance, in one Seek the Keep encounter there are 8 kobolods, the fight is meant for 4 players - so for 3, just use 6 kobolds. For random encounters and 'patrols' deduct one monster per missing player. That sort of thing.

And, yes, some HotDQ encounters are a little overly tough, a few calculate out to 'deadly' using the encounter guidelines in the DM basic pdf, for instance. You can always just go over and re-design them using those guidelines (I suppose they may not have been available in that form to Kobold Press when they were writing the module.)

 

[Tormyr]

I don't know if it is universally applicable, but HotDQ has a note on the Dragonclaws (CR1) that you can change them to Dragonwings (CR2) by doubling their hit dice (and therefore their hp). This may work for other CR1 creatures. Some form of this might also work for creatures of other CR values.