Frost Breath Dragon

Flying, trample, Hexproof, Vigilance
At the beggining of your upkeep, you may tap
target non-land permanent an opponent controls.
It does not untap during it's next untap step.
Whenever this creature is blocked or blocking
another creature, tap that creature. It doesn't
untap during it's untap step.
{4}{u}: Destroy target permanent tapped
by this creature.