Henkan, Under Yoake

Polymorph (This card gains the creature types of every creature you control.)
Boshido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)
{w}: Target creatutre becomes white in addition to its other colors until end of turn.
{1}{u}: Tap target white creature. That creature doesn't untap during its controller's next untap step.