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
Cards like Etali, Primal Storm and The Ruinous Powers will help you cast cards from exile
Depending on your creature count, he grants your entire team extra power and abilities that make them harder to block
With Kefnet, I used those cards to keep a full seven cards in hand so Kefnet could go into combat
Upgrading the Ursulas Return Sapphire/Steel Starter Deck For this Amber/Amethyst Starter Deck upgrade, well do things in a different order
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