Casthus Duendalos

Evasion. If Casthus is subjected to an effect that allows him to make a Dexterity saving throw to take only half damage, Casthus instead takes no damage if he succeeds on the save and only half damage if he fails. Casthus can't use this trait if he has the Incapacitated condition.

Multiattack. Casthus makes three attacks, using Rapier or Firebolt in any combination.

Rapier. Melee Attack Roll: +12, reach 5 ft. Hit: 19 (3d8 + 6) Piercing damage, and Casthus has Advantage on the next attack roll he makes before the end of this turn.

Firebolt. Ranged Attack Roll: +10, range 120 ft. Hit: 22 (4d10) Fire damage.

Spellcasting. Casthus casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 18, +10 to hit with spell attacks):

At will: Message, Thaumaturgy

1/day each: Darkness, 

Fiendish Charm. Wisdom Saving Throw: DC 18, one creature Casthus can see within 30 feet. Failure: The target has the Charmed condition until the start of Casthus’ next turn.

Riposte. Trigger: Casthus is hit by a melee attack roll while holding a weapon. Response: Casthus adds 6 to his AC against that attack, possibly causing it to miss. On a miss, Casthus makes one Rapier attack against the triggering creature if within range.