Omen Machine | Magic: The Gathering
Formats Omen Machine is Legal in
Official Oracle Text for Omen Machine
At the beginning of each player's draw step, that player exiles the top card of his or her library. If it's a land card, the player puts it onto the battlefield. Otherwise, the player casts it without paying its mana cost if able.
Official Rulings for Omen Machine
6/1/2011 : If the player is unable to put the land onto the battlefield (this is rare) or cast the spell (perhaps because there are no legal targets available) as the triggered ability of Omen Machine resolves, the card simply remains in exile.