Multiattack

The shoggoth makes four Slam attacks. It can replace two Slam attacks with a use of Crush.

Slam

Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 30 (4d10 + 8) bludgeoning damage, and the target is grappled (escape DC 18) if it is a Large or smaller creature.

Crush

The shoggoth crushes up to two creatures it is grappling by rolling them beneath its bulk. Each target must succeed on a DC 19 Strength saving throw or take 30 (4d10 + 8) bludgeoning damage, be unable to breathe, and be restrained until the grapple ends. If the shoggoth moves, a creature beneath it is no longer restrained and is able to breathe, but it remains grappled.