Lulu, Black Mage

Imprint - Whenever you cast a blue, black, or red instant or sorcery, you may exile that card with a mage counter on it.
{t}: You may cast a copy of a spell in exile with a mage counter on it by paying its mana cost. Spells you cast this way have replicate. The replicate cost is equal to its mana cost.
"So, how shall we do this?"