Bog Troll

Keen Smell. The troll has advantage on Wisdom (Perception) checks that rely on smell.

Regeneration. The troll regains 5 hit points at the start of its turn. If the troll takes fire damage, this trait doesn't function at the start of the troll's next turn. The troll dies only if it starts its turn with 0 hit points and doesn't regenerate.

Multiattack. The troll makes two attacks: striking once with an improvised weapon and once with a fist.

Improvised club. Melee Weapon Attack: +5 to hit, 1 target, 1d8+3 bludgeoning damage.

fist. Melee Weapon Attack: +5 to hit, 1 target, 1d6+3 bludgeoning damage.

Om nom nom: as a bonus action you can attempt to swallow a creature that is maximum 1 size smaller than you. It must succeed on a dexterity saving throw [DC 12] or be stuck in your mouth for d6 rounds. every round that you have a creature swallowed your regeneration is doubled and the swallowed creature takes 1d4 acid damage at the start of it's turn. the swallowed creature can attempt to break free on it's turn by succeeding a strength check against your strength DC [DC14], upon succeeding the saving throw they are spit out 20ft by the bog troll.

Long tongue: You can take an opportunity attack whenever a creature willingly goes out of 15ft from you as a reaction action the frog-like creature can strike you with it's tongue for 1d6+3 acid damage.

oppertunity attack: whenever a creature willingly leaves your melee range (5ft) you can use your reaction to strike once with the club for 1d8+3 bludgeon damage.