During combat, this ally can copy any one magical item or artifact attached to the opposing champion.
Copyrights:
TSR
Wizards of the Coast
This card can be very useful, but there are many times it won't help. The most potent items to copy would be the ones to instantly win battles, but most of those have discarded your champion already, such as a Blamblower.
The most likely cards to copy and get strong value would include The Winner's Cape (520/4th), Vorpal Blade (56/FR), or any item the opponent stole from you. However, this card does have one major heel.
The opponent must play a magic item or artifact into the battle, or even have a battle worthy. Many decks these days are pure outside of combat use, such as the Rings of All Seeing (171/4th), the Dragon Font (20/AR-chase), or the Bag of Beans (11/NS-chase).
However, in fun play, this card will usually be useful. Note, it can choose to play this ally before it has something to copy, but it won't help until one is played against it. Therefore, usually it is a bad idea to play it before your opponent plays one.
