Triskelion is a rare Artifact Creature — Construct card from Mirrodin (MRD), collector number 269. Current market price: $0.42 (foil $11.43), 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.