Judgment Dragon

Unless you have 4 or more legendary creatures
with different names in your graveyard,
Judgment Dragon can't be cast.
Flying, vigilance, trample
At the beginning of your end step, mill 6 cards.
Pay 5 life: Destroy all other nonland permanents. Activate this ability only while you have 20 or
less life, and only when you could cast a sorcery.