Actions

Clavicus uses actions upto all his SP are spent. In the absence of pillars, Clavicus only has 1 SP.
Diabolic Chains (2 SP) Ranged Spell Attack: +8 to hit, range 60 ft., one target. Hit: 6d6 Hellfire damage.
Flame of Avernus (2 SP) In a cone of 15 ft. all creatures must make a DC 16 DEX Save . Fail = 8d6 Hellfire damage, Suc = 1/2 dmg. (Lair included in the attack
Igniting Bolt (1 SP) Melee/ranged Spell Attack: +8 to hit, reach 120 ft., one target. Hit: 3d10 Fire damage.
Infernal Battleaxe (+2) (1 SP) Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 1d10+6 slashing damage plus 4d6 Hellfire damage.
Incinerate (3 SP) (Recharge 6) In a 10 ft. radius pillar upto 40 ft., targets must succeed a DC 16 DEX Save, or take 12d6 Hellfire damage (Lair included in the dmg).
Ascended Form Clavicus gains 66 temp HP when he turns into his Ascended Form (lost when transforming back). He also casts a delayed Incinerate as a Lair Action and doubles its radius to 20 ft. In the Ascended Form, Clavicus gains the actions below.
Multiattack Clavicus can attack three times with his Claws.
Claws Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 3d6+5 slashing dmg, plus 4d6 Hellfire dmg when near Pillars.
Pillars of Flame Four lines of Fire of 20 ft. each erupt from Clavicus. Each creature in the line must succeed a DC 16 DEX Save or take 6d6 fire damage.
Punish Divinity After taking Radiant damage, Stuns the attacker allowing Clavicus to use his Soul Drain on the target without it being able to Save.

Legendary Actions

Misty Step Ascended: Soul Drain ( 6d6 ) necrotic dmg and heal an equal amount. If not Punished target must succeed a DC 16 CON Save to evade the effects.