Multiattack

The elemental makes two slam attacks.

Slam

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.

Whelm

The elemental targets each Large or smaller creature in its space. Each target makes a DC 15 Strength saving throw. On a failure the target is grappled (escape DC 15). Until this grapple ends the target is restrained and unable to breathe air. The elemental can move at full speed while carrying grappled creatures inside its space. It can grapple one Large creature or up to four Medium or smaller creatures.