Quote from Sheriff-K »Why do you say that? What non-Permanents do you think are necessary? There's only a few I was considering, like the aforementioned Primal Surge.
I'm tempted to run Pact of Negation, just in case. And a Villainous Wealth for value. I also plan to include Crop Rotation, because I want to focus on a Land-type strategy, imploying Dark Depths and Realm Seekers.. Not sure how useful that could be, but it's one of my favorite Cards, so I figured I may as well finally make use of it in Commander. Also, I will probably put a Tabernacle in the deck. (Is GSZ worth running, so we can T1 ramp via Dryad Arbor?)
There are plenty of cards that are great for Muldrotha that justify not being 100% in on permanents. Just to name a few: Cyclonic Rift, Intuition, Fact or Fiction, Forbidden Alchemy, Forbid, and Gifts Ungiven.
One thing that is, in fact amazing about Muldrotha is that Instant and Sorcery spells are dead cards in the graveyard because you can run Snapcaster Mage or Archaeomancer to return them to your hand or cast them again.
Trying to just slam 100% permanents + Primal Surge is a great way to kneecap the true potential of your deck.