Junkyo Bell is a rare Artifact card from Champions of Kamigawa (CHK), collector number 258. Current market price: $0.27 (foil $1.33), TCGplayer market prices via Scryfall.
At the beginning of your upkeep, you may have target creature you control get +X/+X until end of turn, where X is the number of creatures you control. If you do, sacrifice that creature at the beginning of the next end step.