Multiattack

3 Slams or 1 Harpoon and 2 Slams.

Slam

Melee Weapon Attack: +9 to hit, 5 ft., one target, 12 (2d6+5) bludgeoning damage + 9 (2d8) cold or poison (hunter's choice) and target is grappled (escape DC 17). Hunter can grapple only one target at a time.

Harpoon

Melee or Ranged Weapon Attack: +9 to hit 5 ft. or range 20/60' one target 12 (2d6+5) piercing damage + 9 (2d8) cold or poison (hunter's choice) and harpoon sticks in target. While harpoon is stuck target takes 7 (2d6) piercing damage at start of each of its turns hunter can't make Harpoon attacks vs. other targets and target and hunter can't move further than 60' away from each other. A creature including target can take its action to detach harpoon by succeeding on a DC 17 Str check. Alternatively cord connecting the leviathan hunter to the harpoon can be attacked and destroyed (AC 10; hp 25; immunity to bludgeoning poison and psychic) dislodging harpoon into an unoccupied space within 5 ft. of the target and preventing hunter from using Recall Harpoon.

Crush

One creature grappled by hunter: 33 (8d6+5) bludgeoning damage (DC 17 Str half).