Heimdallr, Sentinel of Velheim

Vigiliance, Heimdallr can't attack or block unless
your favor towards white and blue is at least 5.
Players play with the top card of their library
revealed. You may play the top card of your
library.
At the beginning of each opponent's upkeep,
untap up to X permanents you control, where X
is the converted mana cost of the top card of that player's library.