Armor Class 16 (natural armor)
Hit Points 171 (18d8 + 90)
Speed 30 ft.
Saving Throws STR +8, CON +9
Skills Deception +5, Insight +4, Intimidation +5, Perception +4
Damage Resistances cold, [object Object]
Damage Immunities fire, poison
Condition Immunities poisoned
Senses darkvision 120 ft., passive Perception 14
Languages Celestial, Common, Infernal, telepathy 120 ft.
Challenge 12
Aura of Torment. Any creature hostile to the excruciarch that starts its turn within 20 feet of the excruciarch takes 10 (4d4) slashing damage, unless the excruciarch is incapacitated.
Devil's Sight. Magical darkness doesn't impede the excruciarch's darkvision.
Magic Resistance. The excruciarch has advantage on saving throws against spells and other magical effects.
Sadism. The excruciarch gains a +1 bonus to attack and damage rolls for each creature it damaged on its previous turn.
Multiattack. The excruciarch makes two Scourge attacks. It can replace one of the attacks with Storm of Steel (if available).
Scourge. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage plus 13 (2d8 + 4) slashing damage.
Storm of Steel (Recharge 4–6). The excruciarch swings its scourge wildly around itself. All creatures within 15 feet of the excruciarch must make a DC 16 Dexterity saving throw. Targets take 31 (6d8 + 4) slashing damage on a failed save, or half as much damage on a successful one.
Vulnerable Gaze. As a reaction to a creature resisting damage dealt by the excruciarch, it turns its gaze on that creature, negating any resistances and immunities that creature has until the start of the excruciarch's next turn.
CoA, p. 249