Chimeric Mass is a rare Artifact card from Scars of Mirrodin (SOM), collector number 141. Current market price: $0.27 (foil $0.80), TCGplayer market prices via Scryfall.
This artifact enters with X charge counters on it. {1}: Until end of turn, this artifact becomes a Construct artifact creature with "This creature's power and toughness are each equal to the number of charge counters on it."