Additionally to what has been already mentioned,
1) It should probably stick to one element. Cost of three of a certain element seems decent, given that you must sacrifice creatures.
2) Sounds like a last-resort method when you seriously need certain cards, like a shield or a miracle, but I don't think it will be widely used, as people plan their decks so that they often don't have to use a last-resort method that would kill some of their creatures. (or would be abused with cheap creatures)
3) Can you explain further how you see the "entire deck is in your hand for one turn"? When I read this, I thought of the screen that shows up when you finish the 500 score quest (choose one of the 12 weapons), but is that what you are thinking of?