Shape-Shifting

Shape-shifting is the magical effect of a creature changing its physical form. Common examples include druid Wild Shape, the polymorph and true polymorph spells, lycanthrope transformations, and shapechanger monsters (doppelgangers, dragons in humanoid form).

General mechanics:

• The creature assumes the physical form of the target shape: size, appearance, speeds, senses, and natural weapons
• The creature uses the new form's physical stats (Strength, Dexterity, Constitution, AC, HP) and own mental stats (Intelligence, Wisdom, Charisma) and own class features and proficiencies to the extent possible
• HP is typically reset to the new form's value; when the shape ends, the original HP returns at the value it was when the shape began (Wild Shape works this way)
• Damage that would reduce the new form to 0 HP forces a reversion; excess damage carries over to the original form for Wild Shape but not for polymorph

Equipment:

• Worn equipment merges into the new form if the form cannot wear it, and the equipment provides no benefits while merged
• The creature can choose to drop equipment, have it fall to the ground, or have it merge — DM's call by spell text
• Magical items lose their effects while merged unless the spell or item specifies continuation

Ending the shape:

• Voluntary reversion as an action (Wild Shape), bonus action, or as the spell allows
• Forced reversion when the form drops to 0 HP
• The end of the spell duration
• A successful dispel magic or similar effect against the shape

Special: True Polymorph: Permanent transformations under true polymorph fully replace mental stats with the new form's stats — the target becomes the new creature, mind and body, until reverted.