Grave of the Spirit Dragon

{t}: Add {c}{c} to your mana pool. You may only activate this abiity every 2 turns.
{c}{c}: Manifest the top card of your library.
Whenever you cast a colorless spell, you may pay {c}{c}{c}. If you do you may search your deck for a colorless spell with converted mana cost X or less in your hand, where X is the amount of manifests on the battlefield.