Spellsync Prism

Spellsync Prism enters the battlefield with two charge counters on it.
{4}, {t}: Counter target spell, exile it instead of putting it into its owners graveyard, and put charge counters equal to that spells converted mana cost onto Spellsync Prism.
Remove X Charge counters from Spellsync Prism, {t}: Cast target spell with converted mana cost equal to X that has been exiled with Spellsync Prism.