The shambling mound is an old-school classic: veteran Advanced Dungeons and Dragons players will remember the Monster Manual illustration that looked like a Christmas tree with a carrot for a nose. Viny quasi-zombies of the swamps and rainforests, shambling mounds are brutes that tramp around indiscriminately ingesting whatever organic matter they come across, vegetable or animal. Oh, and also beating people up.
Oddly for such a large, ungainly creature, the shambling mound has proficiency in Stealth, which I have to attribute to its natural camouflage. Being a plant without normal senses, it’s immune to blindness and deafness, along with exhaustion. It has blindsight in a 60-foot radius, is resistant to cold and fire damage (that’s one hardy plant), and not only is immune to lightning but actually absorbs the electrical energy and uses it to regenerate.
According to the Monster Manual flavor text, shambling mounds don’t pursue prey but rather wait for prey to come within reach, but for creatures that must feed all the time—and also have “shambling” in their name—this seems like a dull way to play them. It may not move around much, but why wouldn’t a shambling mound be trudging through the woods when the player characters encounter it? Of course, whether it’s waiting or walking, it does so as stealthily as it can, in order to gain the element of surprise against its prey.
The tactical combination is neatly laid out in the shambling mound’s action features. Its Multiattack lets it make two slam attacks (at a formidable +7 to hit); if both attacks hit, its target is grappled, and it gets to Engulf in the same turn, blinding, restraining and suffocating its target. As long as the target remains grappled, the shambling mound continues to Engulf it—and probably shambles away, since it’s got what it came for, and it can’t both Engulf and Attack in the same turn except as part of that specific Multiattack combo. If the target gets free, the shambling mound repeats its Multiattack against it, or against some other target that happens to be within reach if its original target has run away to a safe distance.
Note that the only sense the shambling mound has to detect the PCs with is its blindsight. Any PC farther than 60 feet from it is effectively invisible to it. If it’s struck by a missile weapon or spell effect from outside this range, it won’t know where it came from, only which side of its “body” hurts. It will use its movement to go in the opposite direction—but if it’s hit from multiple directions, and these send conflicting signals about which way it should go, it will either average them out or simply stop moving altogether. On the other hand, if it’s attacked from within its blindsight range, it will move toward its attackers and try to whomp them. This goes double for anyone attacking it with lightning damage. It likes lightning damage. It will move full speed toward the source, hoping for more, even if that source is beyond its sensory radius.
“If a shambling mound faces defeat before an overwhelming foe, the root-stem can feign death, collapsing the remains of its mound,” the MM flavor text tells us. My standard threshold for serious injury is 40 percent of maximum hit points, which in the shambling mound’s case means it’s been reduced to 54 hp or fewer. (If that sounds like a lot, consider that the PCs will have dealt it at least 82 hp of damage already.)
Next: succubi and incubi.