Barrel Down Sokenzan is a common Instant — Arcane card from Saviors of Kamigawa (SOK), collector number 94. Current market price: $0.13 (foil $0.66), TCGplayer market prices via Scryfall.
Sweep — Return any number of Mountains you control to their owner's hand. Barrel Down Sokenzan deals damage to target creature equal to twice the number of Mountains returned this way.