Phantom Blade

Equipment that kills something the moment it lands is doing two jobs a color usually splits across two cards, and this one folds them into a single five-mana artifact: attach on entry, destroy a creature on entry, then keep buffing whatever it rides on. The enters trigger is the real value spike, because it fires once and cannot be recaptured; the equip cost of two exists so that after the initial creature dies or the target changes, moving the blade to a new body is a resource, not a bonus removal spell. Menace on top of the +1/+1 is the aggressive tell: the whole package is built to make a creature both a threat and a piece of removal, so the equipped body wants to be attacking, not sitting back. The "up to one" clauses on both attach and destroy are what keep it from being a dead card in an empty board state; you can cast it with no creature to hold it and no target to kill, and it will still glue itself to a future creature via the equip cost. It reads like a discount on stapling an aura-style removal effect to a repeatable equip chassis, which is the puzzle every removal-on-a-permanent design faces: how to reward the first cast without letting the object keep generating value every time it hops to a fresh creature. The finality is front-loaded, and everything after is just a body wearing a knife.