Merlin of the Tower

{t}{w}{u}Draw 3 cards, then discard 1 card.
{w}{w}Creatures you control gets +1/+2 until end of turn.
{u}{u}Tap target creature, it doesn't untap during their owner's next untap step.
Tap a knight you control, it gains protection from everything until end of turn, activate this ability only once per turn.