Ertai's Meddling is a rare Instant card from The List (PLST), collector number TMP-61. Current market price: $0.79, TCGplayer market prices via Scryfall.
X can't be 0. Target spell's controller exiles it with X delay counters on it. At the beginning of each of that player's upkeeps, if that card is exiled, remove a delay counter from it. If the card has no delay counters on it, the player puts it onto the stack as a copy of the original spell.