Ancient Blue Dragon

Flying
When Ancient Blue Dragon enters the
battlefield, reveal the top 3 cards of your library.
If any of those cards were dragons, Color Shift 6
(When a card triggers color shifting, reveal the top 6
cards of your library. Place each card in piles of the
same color face-up. Then, choose one card from each
color pile and put it into your hand. Put the rest of the
cards into your graveyard.)