Mirror March is a rare Enchantment card from The List (PLST), collector number RNA-108. Current market price: $2.76, TCGplayer market prices via Scryfall.
Whenever a nontoken creature you control enters, flip a coin until you lose a flip. For each flip you won, create a token that's a copy of that creature. Those tokens gain haste. Exile them at the beginning of the next end step.