This card is extremely useful in taking back the upper hand over an opponent who is using a very powerful monster. The equipped monster only has to be half as strong as the one it is attacking in order for it to be able to destroy the opponent's monster by battle. Even outstandingly strong monsters like "Rainbow Dragon" can be taken down with relative ease this way.
This card also works tremendously when equipped to a monster that does Piercing damage, such as "Cyberdark Horn" or "Ancient Gear Golem", because it greatly increases the amount of battle damage this card does to a defending opponent.
This card works exceptionally well with monsters that revive the fallen enemies onto your side of the field, such as Goyo Guardian, Red-Eyes Zombie Dragon, and Paladin of the Cursed Dragon. Goyo Guardian is perhaps the best at doing this, since the opposing monster must have an ATK of 5950 or higher to survive the attack (which few monsters can attain without the aid of support cards).
You can use this card to combat your opponent's Honest. They'll gain your ATK points (your monster's former ATK (without Metalmorph) +300) but you'll gain half of their new ATK points.