Tidal, Dragon Ruler of Waterf.

If this card is exiled, you may search your library for 1 blue dragon creature card and place it in your hand.
{2}{u}: Cast this card as a sorcery, discard this card and 1 blue creature card, search your library for 1 card and place it in your graveyard. You cannot cast this card as a creature spell or use its ability this turn.
You may exile 2 blue or dragon creature cards from your hand or graveyard to cast