Bear Trap

The one-mana cost here buys nothing but a threat held in reserve. The artifact enters cheap, but the kill costs three mana and a tap on top, so the full price to remove a creature is four mana and change spread across two payments. What flash actually purchases is the option: drop it during an opponent's turn to hold up removal, or slam it end-of-step as a mana sink when the turn would otherwise go to waste. The effect is a colorless three-damage burn attached to a permanent shell, priced near a Lightning Strike in total but split so that deployment and detonation happen at different moments. That split is what changes the strategic axis. You pay up front to make the answer available on demand, then pay again to fire it, which turns what would sit dead in hand into a board object that lingers as a standing threat until you spend it. The three-damage cap keeps it from touching anything with higher toughness, and the sacrifice clause makes it a one-shot rather than a repeatable turret. As a colorless artifact it slides into any color pairing that wants creature removal without spending a colored slot, and the flash timing lets it answer at instant speed the way most cheap artifact removal cannot. The trade is deliberate: cheaper to deploy than to use, patient rather than tempo-positive.