Rotted Treant (5e Creature)
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Huge undead, neutral evil
Damage Vulnerabilities fire
Undead Fortitude. If damage reduces the treant to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the treant drops to 1 hit point instead.
False Appearance. While the treant remains motionless, it is indistinguishable from a normal, rotting tree.
Siege Monster. The treant deals double damage to objects and structures.
Multiattack. The treant makes two slam attacks.
Slam. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 16 (3d6 + 6) bludgeoning damage.
Rock. Melee Weapon Attack: +10 to hit, range 60/180 ft., one target. Hit: 28 (4d10 + 6) bludgeoning damage.
Poison Breath (Recharge 5-6). The treant exhales poisonous gas in a 60-foot cone. Each creature in that area must make a DC 15 Constitution saving throw, taking 42 (12d6) poison damage on a failed save, or half as much damage on a successful one.
Cursed by necromancy into a state of living decay, these big, lumbering, bark-skinned husks stay motionless for years, even centuries, until it senses living creatures wander into its territory. It then creaks and cracks slowly to life, its festering, poison-ridden form shambling forward with malicious intent. In its newfound state, the treant's connection to nature is permanently severed, preventing it from calling upon its fellow trees as it once did.