Shadowverse

It's unclear why she's legendary. In terms of power and effect, she's almost an exact copy of the Disaster Witch, with adjustments to stats and cost. And that one is silver.

The Cerberus puppies provide shadows when played, which is quite useful for the Dungeon faction (sorry for the tautology).
By the way, I checked the collection to see the Disaster Witch - I was surprised to find six(!) of her anime copies. I clicked "Liquify Extras," dusted them off, and returned - there were still six of them. I was puzzled. Only now did it dawn on me that extra animations don't take up space, no matter how many there are.