Absorption of the Dead

You may only play this card if you have creature cards in your graveyard. Banish creature cards in your graveyard, and add up their collective cost together, and play something within that cost, but only one card.
(For example, 3 creatures costing {b} equal 3 {b} total, while 1 creature costing {w}{w} and 1 creature costing {r} equals {w}{w}{r})