Isamaru can make a formidable Voltron deck as well, with its low cost for a 2/2, throwing great equipment and auras at it can quickly overwhelm your opponents if they can't deal with it quickly, or let it sit thinking it's not that big of a threat
Sephiroth, the Savior (Atraxa, Grand Unifier) This one I'm surprised at as well, but because of how low it is
No, you cannot mutate a creature with shroud
Best friends with Acererak the Archlich: If you can find a way to make that extra mana for free you can just keep looping it and win the game unless your opponents can do anything about it
Jonah Jameson had any more of it, hed be a Food token
That means you cast a five-mana planeswalker and still hold up interaction on your opponents turn