Recurring Retort

Stockpile {u} (Exile this card from your hand: It gains "{u}: Put a cache counter on this card. Activate this ability only any time you could cast a sorcery" and "You may cast this card from exile. It costs {u} less to cast for each cache counter on it.")
Counter target spell. If Recurring Retort was cast with no cache counters on it, exile Recurring Retort with a cache counter on it.
"You really don't know when to give up, huh?"