Blighted Treant

Blighted Appearance. While the treant remains motionless, it is indistinguishable from a dead tree.

Siege Monster. The treant deals double damage to objects and structures.

Corrupting Presence. An unnatural aura of blight  directly surrounds the treant. Any creatre within a 5-foot radius of the treant mst make a DC 14 Constittion saving throw or be poisoned for 1 minute. A creature may repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. The blights radius expands by 5 feet for ever turn the treant doesn't move.

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. Ranged Weapon Attack: +10 to hit, range 60/180 ft., one target. Hit: 28 (4d10 + 6) bludgeoning damage.

Corrosive Spray (Recharge 5-6). The blighted treant sprays acid in a 15-foot cone. Each creature in the cone must make a DC 13 Dexterity saving throw, , taking 22 (5d8) acid damage on a failed save, or half as much damage on a successful one.

Blight Nature (1/Day). The treant magically corrupts one or two trees it can see within 60 feet of it. These trees have the same statistics as a treant, except they have 60hp, Intelligence and Charisma scores of 1, they can't speak, and they have only the Slam action option. A blighted tree acts as an ally of the treant. The tree remains animate for 1 day or until it dies; until the treant dies or is more than 120 feet from the tree; or until the treant takes a bonus action to turn it back into an inanimate tree. The tree then falls over, now dead and decayed.