Multiattack

Three Slam or Water Blast attacks. If it hits one Large or smaller creature with two Slam attacks the target must make DC 15 Str save or be flung up to 15 ft. to an unoccupied space the troll can see and knocked prone.

Slam

Melee Weapon Attack: +7 to hit, 5 ft., one target, 14 (3d6+4) bludgeoning damage.

Water Blast

Ranged Spell Attack: +5 to hit, 60 ft., one target, 11 (2d8+2) bludgeoning damage + 3 (1d6) cold.

Surge (Recharge 5-6)

Pushes water surge in 30' line × 10 ft. wide. Each creature in line: 28 (8d6) bludgeoning damage and pushed up to 15 ft. from troll in direction following line (DC 15 Str half not pushed). Surge lasts until start of troll's next turn and any creature in line must spend 2 feet of move per 1 foot it moves when moving closer to troll. If troll uses this while underwater creatures in line have disadvantage on the save and any creature in line must spend 4 feet of move per 1 foot it moves when moving closer to troll.