Large Plant
Armor Class 15
Hit Points 123 (13d10+52)
Speed swim +20, walk +20
Challenge 6
Skills stealth +3
Damage Resistances cold, fire, piercing
Damage Immunities lightning
Condition Immunities blinded, deafened, fatigue
Senses blindsight 60 ft. (blind beyond this radius), passive Perception 11
Lightning Absorption. When the shambling mound would be subjected to lightning damage, it instead regains hit points equal to the lightning damage dealt.
Multiattack. The shambling mound takes two slam attacks. If both attacks hit one Medium or smaller creature the target is grappled (escape DC 15) and the shambling mound uses Engulf against it.
Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.
Engulf. The shambling mound absorbs a Medium or smaller grappled creature into its body. The engulfed creature is blinded restrained can't breathe and moves with the shambling mound. At the start of each of the shambling mounds turns the target takes 11 (2d6 + 4) bludgeoning damage.
Source: Level Up Advanced 5e Monstrous Menagerie · OGL/Open