Ashiok, Nightmare Weaver

A mill planeswalker that doesn't actually care about decking you out, and that inversion is the whole design. The plus exiles three cards off an opponent's library, which reads like a clock until you notice where those cards go: they sit in exile, tagged as Ashiok's, waiting for the minus to put any creature among them directly onto the battlefield as a Nightmare under your control. The opponent's library becomes Ashiok's reservoir. You are not racing to empty the deck; you are strip-mining it for the best creature you can find, then fielding your opponent's threats with no regard for their colors or your own. Because the creature arrives on the battlefield rather than being cast, there is no spell to counter and no cast trigger for an opponent to interact with: by the time it matters, the theft is already complete. Each exiled card you steal back is also one fewer the opponent ever sees, so the attrition and the larceny run on the same engine. The ultimate, exiling all hands and graveyards, is a lock that mostly punctuates a game already decided, but the loyalty math gets there fast: the plus builds toward it while stocking the fuel for the minus, and a planeswalker that grows itself while feeding two win conditions rarely needs the emblem-tier payoff to matter. The minus is the reason the card endures: it turns a defensive, grinding shell into something that wins with the opponent's own creatures.