Activate this card by targeting 1 Machine-Type monster on the field; it gains 500 ATK. Once, negate a Spell effect that targets that monster. When that monster leaves the field, destroy this card.
Rulings
Individual Card FAQs
If you chain "Rare Metalmorph" to an effect like "Snatch Steal" that targets a monster, "Snatch Steal" is equipped but its effect is negated while "Rare Metalmorph" is active.
If a monster targeted by "Rare Metalmorph" is flipped face-down, it is no longer targeted by "Rare Metalmorph" and "Rare Metalmorph" remains on the field meaninglessly.
Trap|
Continuous