Bladecoil Serpent is a mythic Artifact Creature — Serpent card from The Brothers' War Promos (PBRO), collector number 229s. Current market price: — (foil $0.55), TCGplayer market prices via Scryfall.
When this creature enters, for each {U}{U} spent to cast it, draw a card. When this creature enters, for each {B}{B} spent to cast it, each opponent discards a card. When this creature enters, for each {R}{R} spent to cast it, it gets +1/+0 and gains trample and haste until end of turn.