D&D 5E Quantifying AOE impact

[FrogReaver]

So, against 2 monsters, an AoE that does damage to each creature equal half the rest of the party's DPR (e.g., a fireball in a scenario where the rest of the party puts out a combined 42 DPR) should prevent 1-2 monster turns.

Against 4 monsters, it should prevent 4-5 monster turns.

Against 6, it should prevent 9-10 monster turns.

Yea, the 4 monster case I computed aligns with yours when fireball is doing half the parties damage.

However, if it's only 40% of the parties damage then I'm getting it's only 3-4 turns.

What do your numbers show for 4 enemies and a fireball doing 40% of party damage?

 

[Esker]

Should be roughly proportional in the share of damage, if you ignore the remainder bit. So 40% of party damage should be 4/5 as many attacks as when it's doing 50%. For 4 creatures, that's something like 3.2-4.2 monster turns. For 6 creatures, 7.2-8.2.

 

[seebs]

It's too situational to get a single overall number. Sometimes you have a lot of weak enemies, and doing 100 damage to one of them is not practically any better than doing 10 damage to one of them, because they're already down at 10.

 

[Esker]

So I guess we could say, roughly, that if the rest of the party's damage is D per round, then an AoE that does PD damage to each of M creatures (changing M here to be the actual number instead of half) should save the party around

P(M^2)/2

monster turns.

 

[FrogReaver]

So I guess we could say, roughly, that if the rest of the party's damage is D per round, then an AoE that does PD damage to each of M creatures (changing M here to be the actual number instead of half) should save the party around

P(M^2)/2

monster turns.

Should be /4 not /2. The /2 get's squared to /4. Right?

 

[Esker]

Should be /4 not /2. The /2 get's squared to /4. Right?

Yeah, but then the P is indexed to 0.5 in the original formula, so if P is 1 you end up with an extra factor of 2.

 

[FrogReaver]

Yeah, but then the P is indexed to 0.5 in the original formula, so if P is 1 you end up with an extra factor of 2.

follow up question, is your formula assuming an enemy that dies on turn X got to act on turn X? Because that will only happen sometimes. So in actuality there's probably a bit of an extra bonus that we haven't yet accounted for?

 

[Esker]

follow up question, is your formula assuming an enemy that dies on turn X got to act on turn X? Because that will only happen sometimes. So in actuality there's probably a bit of an extra bonus that we haven't yet accounted for?

Yes. Though that would apply to either single target or multi-target damage.

And interact with initiative bonuses and so on. Probably not worth trying to model.

 

[FrogReaver]

Yes. Though that would apply to either single target or multi-target damage.

Yea.... Possibly at different break points, but you are right the net effects should be similar. Might be important to consider before comparing to control spells though.

 

[FrogReaver]

It's too situational to get a single overall number. Sometimes you have a lot of weak enemies, and doing 100 damage to one of them is not practically any better than doing 10 damage to one of them, because they're already down at 10.

Most of the time you aren't fighting horde after horde of 10 hp enemies - and if you are then you already have a good idea of how impactful fireball will be.

The non-trivial question about fireball starts to take place in the range where fireball doesn't outright kill the enemies. That's really the area we have been examining - and coincidentally what you will typically find to be the most common situations you face.