Zen Mode (ability)
Zen Mode changes the ability-bearer's form to
Zen Mode when their health falls below 50%.
Currently it only applies to Darmanitan, whose form change makes it Fire/Psychic type and changes its stats around.
Black 2/White 2
|Changes the Pokémon’s shape when HP is halved.|
|X/Y||Changes the Pokémon’s shape when HP is half or less.|