Multiattack

The cavelight moss makes two Tendrils attacks. If both attacks hit a Large or smaller creature, the target is grappled (escape DC 15). Until this grapple ends, the target is restrained, and at the start of each of the target's turns, it must succeed on a DC 15 Constitution saving throw or suffer one level of exhaustion. The cavelight moss then gains 5 temporary hp. A creature that succeeds on the saving throw can't suffer further levels of exhaustion from the cavelight moss's grapple for the next 24 hours. The cavelight moss can have only one creature grappled at a time.

Tendrils

Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) bludgeoning damage.