Mana Clash is a rare Sorcery card from Ninth Edition (9ED), collector number 203★. Current market price: — (foil $15.06), TCGplayer market prices via Scryfall.
You and target opponent each flip a coin. Mana Clash deals 1 damage to each player whose coin comes up tails. Repeat this process until both players' coins come up heads on the same flip.