Mairsil, the Pretender is a mythic Legendary Creature — Human Wizard card from Commander 2017 (C17), collector number 41. Current market price: — (foil $0.41), TCGplayer market prices via Scryfall.
When Mairsil enters, you may exile an artifact or creature card from your hand or graveyard and put a cage counter on it. Mairsil has all activated abilities of all cards you own in exile with cage counters on them. You may activate each of those abilities only once each turn.