Crystal Troll

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

Heavy. If the troll is moved involuntarily by an effect or otherwise the distance it is moved is halved. In addition, the troll has vulnerability to bludgeoning damage taken from falling.

Crystal Spikes. The troll has sharp points all over its quartz-like hide. If a creature grapples the troll (or vice versa) or otherwise comes in physical contact with its skin while it retains its spikes the creature takes 5 (2d4) piercing damage. If the troll uses its Shard Shot action, it loses this trait until it regains hit points from its Regeneration trait.

Regeneration. The troll regains 10 hit points at the start of its turn. If the troll takes thunder damage, bludgeoning damage from weapons made from metal or magical bludgeoning 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.

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.

Shard Shot. As an action on its turn, the troll can shoot its razor-sharp spikes off its hide. Each creature within 10 feet of the troll must succeed on a DC 14 Dexterity or take 26 (8d4 + 6) piercing damage. The troll cannot use this action again until it regains hit points from its Regeneration trait.