Pantheon, Demon of Targon

Flying, trample, protection from Dragons
You may exert Pantheon, Demon of Targon as it attacks. (It won't untap during your next untap step.)
When you do prevent combat damage dealt to Pantheon, Demon of Targon this turn.
Whenever you exert a creature, look at top three
cards of your library. Put one of them into your
hand and the rest into your graveyard.