Actions

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 3d6 piercing damage. When the target is Medium or smaller they have to make a strength saving throw (DC13). On a failed save they are swallowed by the leech.   Swallow. A swallowed target is blinded and restrained. It has total cover against attacks and other effects outside the leech. The creature takes 2d6 piercing and 2d6 poison damage at the start of each of the leech's turns. The leech can have only one target swallowed at a time. if the leech dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 6 feet of movement, exiting prone.

Suggested Environments

Leeches can be found swimming through murky waters and crawling through the mud. In some places people use them for medicinal purposes. Their gigantic variation is often encountered in swamps and sometimes on other planes of existence where the planar magic changes their physical size.