We've added a ton of sweet planeswalkers to the deck, all of which care about running lots of, like Domri, Anarch of Bolas
The First Doctors ability to add +1/+1 counters is likely to mostly be used on creatures, but its nifty to think about putting it on Vehicles like the TARDIS
Cards like Mycosynth Lattice or Trinisphere push Karn from irritating to game-ending, and the fact that this happens without attacking explains why he ranks among good planeswalkers, arguably one of the best to ever get printed for artifact-heavy metas
I think Lathliss will see the most play as part of the 99 of The Ur-Dragon, or even Zirilan of the Claw, though she also does fine as a commander
This one fits into basically any white deck and provides a key additional option that isnt Trouble in Pairs, Esper Sentinel, Mask of Memory or Skullclamp
Cards like Etali, Primal Storm and The Ruinous Powers will help you cast cards from exile