Eye of Ojer Taq #15

T: Add one mana of any color. Craft with two that share a card type 6 (6, Exile this artifact, Exile the two from among other permanents you control and/or cards from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Apex Observatory enters the battlefield tapped. As it enters, choose a card type shared among two exiled cards used to craft it. T: The next spell you cast this turn of the chosen type can be cast without paying its mana cost.