Bog Creeper

Lightning Absorption. Whenever the bog creeper is subjected to lightning damage, it takes no damage and regains a number of hit points equal to the lightning damage dealt.

Burrow. The bog creeper can hide as a bonus action in plain site if the terrain is swamp, bog or any still shallow water. The creeper also gets +5 to stealth checks in these areas.

Multiattack. The bog creeper makes two slam attacks. If both attacks hit a Medium or smaller target, the target is grappled (escape DC 14), and the bog creeper uses its Engulf on it.

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

Engulf. The bog creeper engulfs a Medium or smaller creature grappled by it. The engulfed target is blinded, restrained, and unable to breathe, and it must succeed on a DC 14 Constitution saving throw at the start of each of the creeper's turns or take 13 (2d8 + 4) bludgeoning damage. If the creeper moves, the engulfed target moves with it. The creeper can have only one creature engulfed at a time.

Toxic Bloom. The bog creeper can let some poisonous gas into the air around it. Every creature within 5ft must succeed on a DC 14 Constitution saving throw, or take 10 (2d6+3) poison damage, and be blinded for 1d4 turns. This action can be done while using hide as a bonus action, whitout revealing its location.