Arcane Troll

Keen Smell. The troll has advantage on Wisdom (Perception) checks that rely on smell.

Regeneration. The troll regains 10 hit points at the start of its turn. If the troll takes acid or fire damage, this trait doesn't function at the start of the troll's next turn. The troll dies only if it starts its turn with 0 hit points and doesn't regenerate.

Innate Spellcasting. Arcane Troll spellcasting ability is Charisma (spell save DC 13, +1 to hit with spell attacks). It can innately cast the following spells, requiring no material components:

At will: Druidcraft, Toll the Dead
3/day each: Blur, Counterspell, Cure Wounds(2nd lv. 2d8 + spellcaster modifier)
1/day each: Blight, Evard’s Black Tentacles

Multiattack. The troll makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) piercing damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.