Mist Dancer is a rare Creature — Merfolk Wizard card from The Lost Caverns of Ixalan Commander (LCC), collector number 44. Current market price: $1.00, TCGplayer market prices via Scryfall.
Flying Other Merfolk you control get +1/+0 and have flying. Encore {5}{U}{U} ({5}{U}{U}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)