Multiattack

Two Slam attacks.

Slam

Melee Weapon Attack: +5 to hit, 5 ft., one target, 10 (2d6+3) bludgeoning damage.

Tentacles

Melee Weapon Attack: +5 to hit, 10 ft., one target, 13 (4d4+3) bludgeoning damage and the target is grappled (escape DC 13). Until this grapple ends the constructor can't use its tentacles on another target.