Multiattack

The shoggoth makes 1d4 + 1 slam attacks. Reroll the number of attacks at the start of each of the shoggoth's turns.

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) and restrained. The shoggoth can grapple any number of creatures simultaneously, and this has no effect on its number of attacks.