This is homebrew, submitted by a member of the community.
Rotted Treant
Rotted Treant
Huge Creature, Neutral EvilHuge Creature, Neutral Evil
Undead Fortitude. If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant damage or from a critical hit. On a success, the zombie drops to 1 hit point instead.
False Appearance. While the zombie remains motionless, it is indistinguishable from a normal rotting tree.
Siege Monster. The zombie deals double damage to objects and structures.
Undead Fortitude. If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant damage or from a critical hit. On a success, the zombie drops to 1 hit point instead.
False Appearance. While the zombie remains motionless, it is indistinguishable from a normal rotting tree.
Siege Monster. The zombie deals double damage to objects and structures.
Actions
Multiattack. The zombie 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 zombie 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.
Multiattack. The zombie 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 zombie 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.
Legendary Actions
Details
Cursed by necromancy into a state of living decay, these big, lumbering, bark-skinned husks of treants stay motionless for years, even centuries, until they sense living creatures wander into its territory. It then creaks and cracks slowly to life, a festering, poison-ridden form shambling forward with malicious intent. In its newfound state, the rotted treant's connection to nature is permanently severed, preventing it from calling upon its fellow trees as it once did. Cursed by necromancy into a state of living decay, these big, lumbering, bark-skinned husks of treants stay motionless for years, even centuries, until they sense living creatures wander into its territory. It then creaks and cracks slowly to life, a festering, poison-ridden form shambling forward with malicious intent. In its newfound state, the rotted treant's connection to nature is permanently severed, preventing it from calling upon its fellow trees as it once did.Shout outs: Stacey, Adam Fowler, Amanda Kettles, Angelo Anderson, Appreciate Witch of Life, AstroLass, bilbens baggo, Brian Nunziato, Bryan Sheairs, Brysen Packer, Bryson Waits, Burlyfighter, Caitlin W., Christopher Allbritton, CJMAXP, Connor, Dalton Elliott, Damon Carrington, Daniel Edwards, David Schraff, Dragons With Jetpacks, Elisa Martinez, eric sun, Ezzela1891, Federica Frezza, Gordon Alexander Fallon, Gundar Wez, Iofire, Irate The Pirate, Jade Arrowood, Jake Lane, Jeremiah Walker, Jess, Joe Dalby, John Nazario, JollyGamer, Jonathan Lekse, Jordan Brazeal, Joshua David Maddox, Justin Snyder, Kerry Melton, Kevin, KFB_Patreon, KingHavok1217, Kingyo Senpai, Kyle Clark, Lisa Tucker, Liz Fontain, Lizzie, Lou Bliss, Luke P, Mario Pizzamiglio, Mark L, Matt Yates, Max Hops, Maxwell Mayer, Michael Hamilton, Millergendraft, mtnman1979@aol.com, Mx Charlie, Mylon Schroder, Nahellion, Nathan, Nicholas Zamora, Nick Soucy, Phil Mehl, Phillip P Torchia, Pythor Sen, R., Rachel Anderson, Ray Bissonnette, Remora Jewel, Robert Rich, Robert Skadsem, Ryan Flagg, SallySparrow132, Sarah Holland, Serafina Moon, Shane Andrews, ShortyMcgibble, Sik Makoyi, Siren, Stefan Gottschalk's, Steve Rosenlund, Stuart, Syn21, That Video Editor Nic, thea musing, Trev909, Vedie V, Vincent Drone, Warren Clarida, Wesley Muncy, XMrMonkyx ., Zachary Burgess-Hicks, zachary gee, Zealot23, Zee Livezey
Their contribution stands as a beacon of hope for all adventurers!

