Triskelion is a rare Artifact Creature — Construct card from Duel Decks: Elspeth vs. Tezzeret (DDF), collector number 57. Current market price: $0.33, 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.