6 Mana Teferi is a trap, as tempting as that ultimate is you're just never going to get it unless you're already in a winning position and the abilities are just not worth it. It's too much of a win-more card, if you want that ultimate so badly just replace it with Teferi's Talent. I'd recommend replacing it with Chandra, Legacy of Fire for its Planeswalker synergies. Similarly Ob Nixilis Reignited just draws you a card every turn with a basic kill ability and a meh ultimate, you can do better than that.

I'd say you want more Planeswalkers that protect themselves and your other walkers, It seems too easy right now for you to just crumble when you become the archenemy. Vronos, Masked Inquisitor, Saheeli, Sublime Artificer, Daretti, Ingenious Iconoclast can all make chump blockers or protect your walkers in other ways. Lolth, Spider Queen likes the ammount of stuff that will be dying as you chump block and can make 2 blockers.

I'd cut Don't Make a Sound and Get Out for better counterspells. Counterspell is like a dollar, and Drown in the Loch can double as a kill spell if needed. Alternatively Ripples of Potential can block much more than a single spell threatening your walkers.

Leyline of the Void is unneeded unless you are really facing a lot of reanimator, It'll sit dead in your hand too often and it's unlikely to make you archenemy (More often you'll just piss off one player while the other two are neutral) like you want.

I'm surprised that you don't have any of the Oath cards in here. Oath of Liliana and Oath of Jace seem like they'd be great.

For creatures Jaya's Phoenix seems like a slam dunk. Saruman, the White Hand makes a pretty big creature when you cast planeswalkers, letting you trade with bigger things and immediately replace it.