certain green friend

Shapechanger. The plant can use its action to polymorph into a Small or Medium humanoid, or back into its true form. Other than its size and speed, its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Amplified Charge. If lightning damage hits the Plant, instead of taking damage it will immediately revert to it's true form and glow a bright yellow. It's Kaboom? attack will deal double damage, and it's range will increase from 60 feet to 90 feet, and the weak radius will extend from 40 feet to 60 feet. 

The Plant does not have arms in it's true form, and instead has two extra legs.

Multiattack. The Plant makes two fist attacks or .

Fist (Humanoid form only) Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) bludgeoning damage.

Kaboom? (Plant form only) The Plant can only use this attack if it is within 5 feet of a hostile creature. When it uses this action, it will flash bright white and start to hiss, and next action will explode. Each creature within 60 feet of it when it explodes must make a DC 15 Dexterity saving throw, taking 35 (10d6) fire damage on a failed save, or half as much damage on a successful one. If the creature is more than 40 feet from the center it will act like it has evasion. The plant that used this will make a DC 15 Constitution saving throw instead of a dexterity one. The explosion ignites flammable objects in that area that aren't being worn or carried.

If the Plant takes fire damage without dying, it can use Kaboom? as a reaction.