Esper is a common Plane — Alara card from March of the Machine Commander (MOC), collector number 49. Current market price: $7.14, TCGplayer market prices via Scryfall.
Artifact spells cost {1} less to cast. Whenever chaos ensues, creatures you control that are white, blue, and/or black become artifacts in addition to their other types until end of turn. Then each artifact creature you control gains vigilance, menace, and lifelink until end of turn.