Exterminator Magmarch is a rare Artifact Creature — Phyrexian Construct card from Modern Horizons 3 Commander (M3C), collector number 124. Current market price: $0.29, TCGplayer market prices via Scryfall.
Whenever you cast an instant or sorcery spell that targets only a single nonland permanent an opponent controls, if another opponent controls one or more nonland permanents that spell could target, choose one of those permanents. Copy that spell. The copy targets the chosen permanent. {1}{B}: Regenerate this creature.