Creating a copy of all your casted nonlegendary creatures is no joke, and getting 15 cards in the grave in a format like Commander is not as difficult as it seems
Do Magic: The Gathering Cards Hold Value
This version of Ezur is fairly mana intensive to get your double proliferation activation, requiring you to pay three mana on top of the four required to cast it
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5 Cards to run with Shadow the Hedgehog Kiki-Jiki, Mirror Breaker: Making quickly disposed of versions of various creatures you control, Kiki-Jiki is a great friend to Shadow
Enter the Bargain, with twice the cost, only skips your draw step, you draw them immediately to cast them or in response to something, and it's even legal as a four of in Vintage where it used to be on the B&R list