Conjure Animals Encounter CR

ZenBear · Jun 19, 2019

I'm working on some homebrew spellcasters, and I want them to have Conjure Animals on their spell list. The question I have is, how do I balance an encounter with this in mind? The spellcaster is only CR 2 by itself, but it can conjure 8 CR 1/4 beasts which immediately turns a Medium encounter for 4 2nd level characters into a Deadly encounter for 4 4th level characters. I understand the party would sensibly focus the caster, but if the caster maintains distance and concentration then it's an easy TPK. How should I handle this? Is it a bad idea to put this spell on a monster? It really fits the spellcaster in question, so I really want to grant it.

Xeviat · Jun 19, 2019

Theoretically, the spells you give a caster shouldn't affect it's CR. In actuality, it very much does. CR is descriptive, not prescriptive in 5E. You're supposed to calculate the damage a character can deal over 3 rounds, then divide by 3 to get an average as part of your CR calculation.

Summons are a lot harder to deal with, since disrupting the spellcaster's concentration is the little mini game in this encounter. If the players go for it, then the encounter could go a lot easier and the summons might just have one round to act. If not, they could be in for a tough fight.

What beasts are you intending on using? What stat block are you using for the caster? What is the composition of your party? These are things you'll want to look at.

ZenBear · Jun 19, 2019

Copy/pasting from D&D Beyond where I'm building this. It's a Plague Priest, from Warhammer: Fantasy, that I'm converting to 5e. I want it to have a version of the Vermintide spell from Total War: Warhammer where they summon a unit of clanrats, but in this case I'm thinking Giant Rats (Diseased) or Swarms of Rats. I intend to use these in multiple campaigns, so party composition will vary.

Armor Class 12
Hit Points 91 (14d6 + 42)
Speed 35 ft.
STR 10 (+0) DEX 15 (+2) CON 16 (+3) INT 10 (+0) WIS 16 (+3) CHA 8 (-1)
Damage Immunities Poison
Condition Immunities Poisoned
Senses Darkvision 60 ft., Passive Perception 13
Languages Common, Undercommon
Challenge 2 (450 XP)

Sunlight Sensitivity. While in sunlight, the skaven has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
Keen Smell: The skaven has advantage on Wisdom (Perception) checks that rely on smell.

Pack Tactics: The skaven has advantage on an attack roll against a creature if at least one of its allies is within 5 feet of the creature and the ally isn’t incapacitated.
Tough: If damage reduces the plague priest to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is from a critical hit. On a success, the plague priest drops to 1 hit point instead.
Pestilent: Devotees of Clan Pestilens are immune to the effects of poison and disease, though they remain capable of carrying such afflictions.
Spellcasting: The Plague Priest is a 5th level caster. It’s spellcasting ability is Wisdom (spell save DC 13, +5 to hit with spell attacks). It knows the following spells:

Cantrips (at-will): Infestation, Poison Spray, Spare the Dying
1st level (4 slots): Bane, Ray of Sickness
2nd level (3 slots): Blindness/Deafness, Ray of Enfeeblement
3rd level (2 slots): Stinking Cloud, Vermintide (Conjure Animals - Rats)

Actions
Multiattack: The plague priest makes two attacks with its plague censer.
Plague Censer. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) piercing damage, and the target must make a DC 13 CON saving throw or contract a disease. Until the disease is cured, the target can't regain hit points except by magical means, and the target's hit point maximum decreases by 3 (1d6) every 24 hours. If the target's hit point maximum drops to 0 as a result of this disease, the target dies.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) piercing damage.

Lancelot · Jun 19, 2019

That is not a CR 2 opponent, IMHO, regardless of conjure animals. If you only look at it's AC, HP and melee attack... it's tougher than a CR 2 ogre. +1 AC, +1 average damage, and +32 (!!) HP.

Plus it has disease, immunities, zombie toughness, pack tactics, and a 5th level caster spell-list. So, let's compare it to some other things...

CR 2 berserker? More HP, more average damage, and still all those special abilities. CR 2 priest? Same spell-casting and 1 point worse AC, but better in every other regard - including more than triple the HP.

I'd guesstimate it at CR 4. More dangerous than a CR 3 knight (more HP, spellcasting, other specials - but worse AC), and less dangerous than a CR 5 gladiator (which is superior in nearly every way except the spells). It's also considerably less dangerous than the CR 6 mage (which is a glass cannon; easily killed in a single round, but bad things can happen if it gets a couple of area-effect spells off).

Usually, CR calculations are best made by looking at a handful of creatures on either side and figuring out whether your target creature is likely to be a less or more deadly foe. CR 4 feels about right to me for this one, given that even 1 round of pack tactics conjure animals could be very dangerous (even lethal) to at least one party member. Also, this guy is packing a potentially lethal disease attack and does surprisingly chunky melee damage as well - and will be around for multiple rounds to use it with his very large HP total and zombie resilience.

ZenBear · Jun 19, 2019

Using the Monster Statistics by Challenge Rating from the DMG, it has 91 HP and 12 AC, putting it squarely in the CR 2 range. The Tough trait (Undead Fortitude) adds 7 effective CR according to the DMG, so it's definitely on the high end but still CR 2. Offensively, it can do 14 damage with its censer putting it in the CR 1 range, +5 to hit bumps that up to CR 2. The disease effect doesn't do immediate damage so it isn't factored in to CR, and its only damaging spell is Ray of Sickness which averages 18 on a 3rd level slot, which arguably makes this guy a CR 3 but I don't intend it to upcast RoS so I think I can low ball it. I tend to run my PCs high powered, with a bonus feat at level 1 and I am generous with magic items, so I don't mind my monsters being on the high end of their CR brackets.

Blue · Jun 19, 2019

ZenBear said:
Using the Monster Statistics by Challenge Rating from the DMG, it has 91 HP and 12 AC, putting it squarely in the CR 2 range.

The difference between theory and practice is that, in theory there's no difference...

In other words, you can arrange elements that come in to a particular CR, but in play it it can be a lot stronger or weaker. Especially depending on the synergies with it's abilities, with it's allies and depending on the PCs that fight it.

Heck, a melee heavy party can find a bunch of foes with a climb speed and ranged attacks to be well above their CR rating in the right environment.

The numbers are there for a guideline - not a proof.

ZenBear · Jun 19, 2019

Blue said:
The difference between theory and practice is that, in theory there's no difference...

In other words, you can arrange elements that come in to a particular CR, but in play it it can be a lot stronger or weaker. Especially depending on the synergies with it's abilities, with it's allies and depending on the PCs that fight it.

Heck, a melee heavy party can find a bunch of foes with a climb speed and ranged attacks to be well above their CR rating in the right environment.

The numbers are there for a guideline - not a proof.

Indeed, and I have run an earlier version of this creature before with three melee mooks as support against a party of newbie players, and it went down in three turns without dealing a tremendous amount of damage, even though it got the drop on them casting Stinking Cloud. In practice, a melee leader is a prime and easily accessible target, so running high on the DCR allows it to have at least a little fun with its various debuffs before it gets focused down.

I was hesitant to drop the stat block for exactly this reason. I’m always grateful for feedback on my homebrew monsters, but right now I’m asking about the Conjure Animals spell specifically. I would very much appreciate a bit more feedback on that.

Blue · Jun 19, 2019

ZenBear said:
The spellcaster is only CR 2 by itself, but it can conjure 8 CR 1/4 beasts which immediately turns a Medium encounter for 4 2nd level characters into a Deadly encounter for 4 4th level characters.

Adding eight CR 1/4 beasts woulds change the CR of the encounter like you say. Having a spell which costs an action to use, precludes use of any other Concentration spell by the caster, and all of the creatures can be lost with a single missed Concentration check - and will be lost with inflicting the "dead" condition on the caster - is not quite as strong.

Also remember that the neutral DM chooses what arrives, not the hostile caster played by the DM. (Clarified in the errata.) Tailor the encounter like you'd tailor any other.

In theory cast spells don't change the CR. We already covered the discussion about theory and practice, so I'd up it. Value them somewhere between nothing and their expected value if they were real beasts, based on how well or poorly you think the party will think and execute going after the caster. That's something outside the CR guidelines, use your feel for your table to estimate.

MechaTarrasque · Jun 19, 2019

Don't forget that the beasts count as fey and are affected by spells like protection from evil and good. That would negate pack tactics on at least one front-liner.

MonkeezOnFire · Jun 19, 2019

As a point of comparison the Guildmaster's Guide to Ravnica gives us the Horncaller which pretty much only casts conjure animals and then uses it's turn to command 1 of them to attack (along with 2 weak melee staff strikes, but generally the spell caster will want to hang back). It comes in it at CR1.