Bog Creeper

Camouflage. The Bog Creeper has +4 to stealth checks made in a dark or swampy environment.

Acidic Stench. All creature within a 20 foot radius must make a constitution saving throw (DC 15) or take 1 d4 poison damage. These effects end after 1 d6 rounds. 

Claws. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 5 (1d8 + 2) [Slashing] damage. 

Fangs. Melee Weapon Attack: +2 to hit, reach 5 ft., 1 target. Hit: 8 (2d6 + 1) [Slashing] damage. 

Poison Spit. RangedWeapon Attack: +1 to hit, range 15/40 ft., 2 targets. Hit: 4 (1d4 + 2) [Poison] damage.

Tough Skin. When taking damage, the Bog Creeper can use it's reaction to make a dexterity saving throw (Difficulty Class 10) to reduce the damage by half. (Round down)

The Bog Creeper's Legendary Actions count as either a special action or an action.

Mud Manipulation (Costs 0 Actions). The Bog Creeper can manipulate mud in order to form a magical shield around itself. The Bog Creeper gains temporary hit-points equal to 2 d20 + 15. (5/day)

Plague Of Insects (Costs 1 action). The Bog Creeper summons a swarm of gnats with a radius of 1d20 + 10 feet. Every time a creature (not including the Bog Creeper) start it's turn, finishes it's turn, or moves into the swarm, it must take 1 d6 + 2 piercing damage. This swarm dissipates after 1 d10 + 5 rounds. (5/day)