Willow Womp

This spell transforms a creature that you can see within range into large willow tree. An unwilling creature must make a Wisdom saving throw to avoid the effect. The spell has no effect on a shapechanger or a creature with 0 hit points.

The transformation lasts for the duration, or until the target drops to 0 hit points or dies. The target transforms into the shape of an awakened tree, and takes all of its stats and attacks, though it retains all languages known. 

The tree's slam attack has a reach of 10 ft, +6 to hit, and does 3d6+4 blugeoning damage. 

The target assumes the hit points (60) of its new form. When it reverts to its normal form, the creature returns to the number of hit points it had before it transformed. If it reverts as a result of dropping to 0 hit points, any excess damage carries over to its normal form. As long as the excess damage doesn't reduce the creature's normal form to 0 hit points, it isn't knocked unconscious.

At each successively higher level the spell is cast, the caster can either increase the HP of the tree by 15 or add an additional d6 to the damage roll. For example, if the spell was cast at 5th level, the caster could choose to give the tree either 70 HP or to allow its attacks to do 4d6+4 damage.

The creature is limited in the actions it can perform by the nature of its new form, and it can't speak, cast spells, or take any other action that requires hands or speech, though it can understand language and sense movement.

The target's gear melds into the new form. The creature can't activate, use, wield, or otherwise benefit from any of its equipment.