Lore and CR for a new Archfey

[Protato]

In a game I'm co-DMing, one of the recurring threats is known as Clothos, a powerful Archfey with the power to cut the silver cord of another being, and has command over demons. However, I don't think Fey are usually known for having demonic minions. If a Fey does, how would they gain them? Also, worth noting is that Clothos was trapped in Pandaemonium, but she returned to the material world because the realm of Pandaemonium had "fused" with the in-game world after the summoning of Tharizdun (long story). I'm just wondering what this might mean for her lore-wise, really. Additionally, she has no CR right now, and I'm rather novice at creating statblocks myself, so I figured the forum might be a good place to turn to when asking about a creature's CR.

Large Fey Abomination, Chaotic Evil


Survivability

AC 18 Natural
HP 182
30ft. speed, 60ft. flight speed


Stats
10/18/16/19/18/22

Charisma Save: +14
Skills: Arcana +7, Deception +12, Insight +7, Perception +7, Persuasion +12
Damage Resistance: Fire, Cold, Lightning, Radiant, Psychic, Nonmagic Weapons
Damage Immunity: Poison
Condition Immunity: Prone, Charm, Poison
Senses: Passive 17, Truesight 120ft.
Languages: Common, Elvish, Abyssal, Infernal, Dwarvish, Sylvan

Innate Spellcaster: DC17, +9 to hit. Uses Charisma.

Magic Resist: Advantage versus spell saving throws.

Call of Pleasant Memories: Once per round upon getting attacked, Clothos summons a manifestation of the memory (stats of a doppelganger) to take the appearance of someone from the attacks past that they remember fondly.

Actions

Claw: +7 to hit, 5ft. reach, 2d6+4 (11 average) Slash damage

Charming Illusion: Clothos can charm 1 creature within 30ft of her. Target must make a DC 17 wisdom save or be charmed. If Clothos tells the creature to harm itself, repeat the saving throw. Succeeding a saving throw makes target immune to Clothos' charm for 24 hours.

Draining Kiss: Clothos kisses a charmed or willing creature. Target must make a DC17 con save or take 4d10+4 psychic damage. Half damage on a successful save. Clothos heals equal to damage done. If target reaches 0 HP from this attack they are dead. If target dies from this attack and the health gained goes over the max HP, increase max HP.

Cut the Silver Cord (Recharge on 6): Clothos pulls a string out of a target creature and cuts it. Target Creature makes a DC 17 con saving throw. On a failed save the target takes 8d10+4 damage. If this attack drops creatures HP down to zero, target creature is dead and cannot make a death saving throw.

Dark Delirium (Recharge on 4): Clothos sends target to an illusory world and must make a Wisdom saving throw with a DC of 17. On a failed save the creature is charmed or frightened for 1 minute. This effect ends early if target takes damage.

Reactions

Misty Escape: When Clothos takes damage she can teleport 60ft away.

Legendary Actions: Clothos has three Legendary Actions.

Recharge (1 Action spent): Clothos recharges all resources spent except HP and Legendary Actions.

Misty Bomb: Clothos throws a green orb that explodes into mist. The mist expands by 20ft, anyone in the mist cannot see and must make a DC 17 con save. A failed save results 4d8+6 poison damage for every turn starting in the mist and target becomes badly poisoned taking 1d8 damage until they use an action make a DC 17 medicine check or wait 10 minutes. Take half damage and do not get poisoned on a successful save.

Spellcasting: 3 level one slots, 2 level two and three slots, one slot for levels four through nine

L1: Charm Person (At Will), Burning Hands (At Will), Disguise Self, Hideous Laughter
L2: None
L3: Fear, Vampiric Touch
L4: Polymorph
L5: Cone of Cold
L6: None
L7: Mirage Arcane
L8: None
L9: None

[Mith]

Is this inspired by the Fate Clotho? You could probably modify a Hag to get what you want.

[Protato]

This character has already been used before though, a few times actually. Right now, she can't be beaten by the party (probably not anyway), but one day they can. As such, I needed a CR. The co-DM didn't think to put one in when she made Clothos.

[nickl_2000]

This character has already been used before though, a few times actually. Right now, she can't be beaten by the party (probably not anyway), but one day they can. As such, I needed a CR. The co-DM didn't think to put one in when she made Clothos.

Probably best to works backwards then. Figure out at what point you want the PCS to be able to challenge and set the CR from that.

[gloryblaze]

A quick and dirty CR crunch:

182 HP is doubled to an effective 364 because the monster has numerous resistances. According to the CR table, we would expect a 364 HP creature to have 19 AC. 18 AC is within 1 step of the expected value, so no defensive CR adjustment is required. That puts the defensive CR of the monster at 20.

Offensive CR is a little trickier: According to the DMG, we can expect a cone-shaped AoE to hit a number of creatures equal to size / 10, and a spherical AoE to hit a number of creatures equal to radius / 5. If we use those numbers, then Clothos's optimal attack pattern is 9th level Cone of Cold -> Misty Bomb (1st LA) -> Misty Bomb (2nd LA) -> Recharge (3rd LA, to regain access to 9th level slot), repeat. The damage breakdown goes like this:

9th level CoC = 12d8 (54) * 6 targets = 324 damage
Misty Bomb = (4d8 (18) + 6) * 4 targets = 96 damage, twice per round

Total 516 expected DPR, which is absurd. A CR 30 creature is only expected to do 320 DPR, but it's the highest possible CR, so it's what we'll use for the base offensive CR. However, the 17 DC save significantly bumps down the offensive CR to 27, as we would expect a CR 30 creature to have a DC of 23.

Averaging defensive (20) and offensive (27) puts us at a final CR of 24.

However, two major caveats:

1) Clothos's DPR is inflated by the number of creatures she can expect to hit with her large, at-will AoEs. If she's hitting fewer than 6 people with each Cone of Cold / 4 people with each Misty Bomb, she won't live up to her theoretical DPR.

2) This attack pattern ignores all of her fun tricks and status conditions in favor of pumping out damage.

As a result of 1) and 2) combined, Clothos probably punches well below offensive CR 27 in actual play*, as the DM likely won't just spam 9th level Cone of Cold, and even if s/he does, a typical D&D party is only 4 people, so DPR will experience a dropoff from the theoretical 6 hit cone.

*A quick glance at some actual mid-20 CR creatures, such as the archdevils and demon lords from MtoF, demonstrates this quite handily - all of them outstrip Clothos's AC and HP, even the ones that are below CR 20, they greatly exceed her in consistent single target damage, and most can even match her bag of tricks with innate spells and nifty abilities of their own. Clothos's CR is definitely artificially inflated by the way AoE damage calculations work.

[Spore]

As for spells, not considering CR:

2: Mirror Image, Invisibility/Darkness, See Invisibility
6: Mass Suggestion, Mental Prison, Programmed Illusion
8: Mind Blank, Dominate Monster
9: Gate (free, but only to the ethereal plane)