Spire Serpent is a common Creature — Serpent card from Mirrodin Besieged (MBS), collector number 32. Current market price: $0.12 (foil $0.30), TCGplayer market prices via Scryfall.
Defender Metalcraft — As long as you control three or more artifacts, this creature gets +2/+2 and can attack as though it didn't have defender.