Chimeric Egg is a uncommon Artifact card from Darksteel (DST), collector number 106. Current market price: $0.23 (foil $0.47), TCGplayer market prices via Scryfall.
Whenever an opponent casts a nonartifact spell, put a charge counter on this artifact. Remove three charge counters from this artifact: This artifact becomes a 6/6 Construct artifact creature with trample until end of turn.