Multi-attack.

The Writhe Wood Tree can make up to three attacks depending on its head count: Using its Vicious Lunge, Flesh Whip, and Woozy Bloom.

Regeneration.

The Writhe Wood Tree regains 7(1d6+4) hit points at the start of its turn if it has at most 10 hit points.

Flesh Whip.

Melee Attack: +3 to hit, reach 5 ft. one target.
Hit: 7(1d6+4) bludgeoning damage.

Vicious Lunge.

Melee Attack: +3 to hit, reach 15 ft. one target.
Hit: 13(3d8+1) piercing damage. The targeted creature must succeed on a DC 13 Constitution saving throw or take an additional 1d6 bleed damage.

Woozy Bloom (Recharge 3–5).

The fleshy blossoms on its heads bloom violently, releasing a nauseous and otherworldly gas. Each creature within 10 feet must make a DC 14 Wisdom Saving Throw, all creatures are to go Unconscious on a failed save and given a disadvantage on their next attack roll if successful. This effect will last until the Writhe Wood Trees' next turn.