Triskelion is a rare Artifact Creature — Construct card from Magic 2011 (M11), collector number 218. Current market price: $0.27 (foil $0.67), TCGplayer market prices via Scryfall.
This creature enters with three +1/+1 counters on it. Remove a +1/+1 counter from this creature: It deals 1 damage to any target.