D&D 5E Figuring the Offensive CR of a Spellcaster

Syntallah · Mar 15, 2015

The DMG says to take three rounds of attacks when computing the offensive CR of a creature. Say I have a sorcerer who plans on casting three Fireballs in the first three rounds of combat...

- Round 1 = 28 (8d6) average damage
- Round 2 = 28 (8d6) average damage
- Round 3 = 28 (8d6) average damage

Now, when computing this guys Offensive CR do I:

a) Take the failed save damage [28] * 3
b) Take the successful save damage [14] * 3
c) Does the area of affect come into play at all? That is, if more than one PC is affected, that can increase the 28/14 per round point values listed above quite dramatically.

Any insight is appreciated.

Minigiant · Mar 15, 2015

A

You use the failed value. After looking at the CR you get, if the monster's DC is within the suggested amount then you're fine.

3 fireballs equals CR 3. If the sorcerer's DC is ~13, you're fine.

Mouseferatu · Mar 15, 2015

Rules are to assume that an area attack hits two PCs, when figuring damage.

Syntallah · Mar 15, 2015

Mouseferatu said:
Rules are to assume that an area attack hits two PCs, when figuring damage.

Mouse, you're a straight shooter, and I don't doubt you for a second, but do you have a page reference for that? I looked for it last night, and couldn't find anything...

Jack99 · Mar 15, 2015

Syntallah said:
Mouse, you're a straight shooter, and I don't doubt you for a second, but do you have a page reference for that? I looked for it last night, and couldn't find anything...

278 and 280 (under the Breath Weapon entry)

Syntallah · Mar 15, 2015

Thanks! I don't feel too bad since I definitely wasn't looking under breath weapon for my spellcaster*..!

*not a dragonborn, lol

Mouseferatu · Mar 15, 2015

Yeah, it's hidden/tucked away in there.

I love 5E, and I don't have nearly the problems with the game's organization or rules clarity that some people do--but it's certainly far from perfect when it comes to laying things out in a logical manner.

Syntallah · Mar 15, 2015

Mouseferatu said:
Yeah, it's hidden/tucked away in there.

I love 5E, and I don't have nearly the problems with the game's organization or rules clarity that some people do--but it's certainly far from perfect when it comes to laying things out in a logical manner.

Agreed, 100%. I have played since 1978, and this is, by far, my favorite addition! It's a 3E chassis, with 4E tweaks, and a 1/2E feel; what's not to love..?!?

Tormyr · Mar 17, 2015

For a while I was trying to figure out the answer to this question. I reverse engineered the various NPC spell casters and some monsters that can cast spells. In the end, the best fit seemed to be that the number of affected creatures comes from the Targets in Areas of Effect table on page 249 of the DMG, and all targets make their save. In the case of a fireball, the damage calculation is the same as taking 2 (from the breath weapon calculation) and they both fail their saves (4 making their saves vs. 2 failing their saves). But cone of cold can cover 6 creatures based on the table, and the damage calculation seemed to following 6 creatures making their saves instead of 2 failing their saves. Other spells like moonbeam or call lightning are only 5 foot radius and would only hit 1 creature based on the table

For the sorcerer, the DPR would be 56 (2 failing their save or 4 making their save, your choice). That starts offensive CR at 8. If the sorcerer has a +4 charisma, it's save DC and attack bonus would both fall into the CR 8 range. +4 Dex and mage armor or draconic heritage would give it AC 17. Finish it off with 180 hp and you have a CR8 sorcerer. Or you give it a defensive CR of 4 and it averages out to 6. The CR system is flexible, and you can nerf 1 section to balance out a strong section.

Another thing to watch would be sorcerer points if you decide to include them. Empowerer would change DPR a bit.

That being said, 2 in an area effect will probably be good enough most of the time.