Eye of Ojer Taq

: Add one mana of any color.
Craft with two that share a card type (, 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.)
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Apex Observatory enters the battlefield tapped. As it enters, choose a card type shared among two exiled cards used to craft it.
: The next spell you cast this turn of the chosen type can be cast without paying its mana cost.