Wrichtar, Winter Master

First Strike, Frostbite (Whenever a creature with
Frostbite is blocked, tap the blocking creature and give it
-1/-1 until end of turn.)

When Wrichtar enters the battlefield or attacks, draw a
card. If the card you draw is a permanent card, you may
pay {2}. If you do, exile that card under Wrichtar,
Winter Master face down.

When Wrichtar leaves the battlefield, you may pay {x}. If
you do, you may play X cards exiled under Wrichtar
without paying their mana costs.