Milling random cards will give pseudo card quality or card advantage, or it can be a mana saving too
I can take my invitation to the Commander Format Panel in the comments below
(When this Equipment enters the battlefield, create a 2/2 red Rebel creature token, then attach this to it.) Whenever Blade of Shared Souls becomes attached to a creature, for as long as Blade of Shared Souls remains attached to it, you may have that creature become a copy of another target creature you control
I'm not sure why they represented a spell with an artifact instead of an enchantment, but they did
Karumonix, the Rat King Mirrodin was meant to be a perfect, metallic plane, but even such a shining plane could never be free of vermin
While it's both hilarious and enjoyable to beat your opponent with their own deck, you're also relying on the synergy of your opponent's deck to gain the upper hand