Chief Engineer is a rare Creature — Vedalken Artificer card from Magic 2015 (M15), collector number 47. Current market price: $0.90 (foil $3.34), TCGplayer market prices via Scryfall.
Artifact spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting an artifact spell pays for {1} or one mana of that creature's color.)