Quote from DeLocke »As much as I love everything about this card, I'm gonna drop two rulings that'll unfortunatly kill a lot of the hype :/
1) Spells with a blank in the cost space have no cost, this isn't the same as a 0 (See Memnite). they cannot be cast and so cannot be used with this spell.
2) Casting a spell must obey all its timing restrictions, so you can only use this with instants and cards with flash. If it let you play a spell, you could throw anything out but unfortunatly it must be cast as per the rules, just ignoring the cost.