Nice unique take on Muldrotha! For starters, I would try to cut as many nonpermanents as possible because the less of those, the more cards you can cast with Muldrotha. I would take out Counterspell, Devious Cover-Up, and Price of Fame and replace them with cards like Lunar Force and Decree of Silence or even Siren Stormtamer and Kheru Spellsnatcher. You could also replace them with plain removal like Pernicious Deed, Oblivion Stone, Hostage Taker, etc. However, I very much like Spelljack because it is so on theme with the deck, keep it in! In terms of ramp, Cultivate and Explosive Vegetation are great choices, but you can get by with using Sakura-Tribe Elder, Wayfarer's Bauble, Khalni Heart Expedition, The Mending of Dominaria for your ramp package. These are useful because, once again, they are repeatable. I would also cut the Llanowar Elves if you add enough other ramp cards. Archaeomancer can be upgraded for Eternal Witness. Bond of Insight, Merfolk Secretkeeper, and Mire Triton feel a little out of place because they only mill a few cards. If you want big mill spells I would put in Mind Funeral and Traumatize and for permanents that mill, Sidisi, Brood Tyrant, Stitcher's Supplier, and Dreamborn Muse from your sideboard are all great cards and to top it all off Mesmeric Orb is a terrific card. If you want more instant and sorcery recurral The Mirari Conjecture is great for that. I'm not sure what Deadeye Navigator and Peregrine Drake are doing for you when they are on their own. Evil Twin, and any cards that copy other creatures are flavorful additions. Lastly, why not just steal their permanents when you can also steal their turns with Mindslaver. I hope my ideas have helped, and I hope you keep improving this deck!

Ooh thanks for all the suggestions Andrew30001! Since this deck is so new, a lot of cards are just ones I already owned. In terms of the counterspell suggestions, I really like the Stormtamer and Spellsnatcher. Siren Stormtamer looks perfect for all the Bojuka Bogs going around in my playgroup, and Kheru Spellsnatcher is another counter that lets me steal the spell for later use.

Speaking of the land searches too, I actually picked up a cheap Expedition Map the other day, I can use that and Sakura-Tribe Elder. However, while I was eyeing up the Saga, The Mending of Dominaria will shuffle my graveyard back into my library which is what I don’t want. I’ll have to look for an Eternal Witness and Mind Funeral for sure.

Devious Cover-Up and Bond of Insight are both for recursion of instants/sorceries but possibly replaceable once I test and see how new cards are interacting. Peregrine Drake alone is admittibly only good if I have the bounce lands out, but Deadeye with any of the etb creatures is great (Gravebreaker Lamia/Gray Merchant of Asphodel/Ravenous Chupacabra etc). Mesmeric Orb is awesome but too pricy if I want to keep this deck budget. Mindslaver is certainly interesting and I’ve seen the constant replaying to keep controlling someone, I don’t particularly want to be playing it. It’s simply not a fun card for whoever I’d be controlling and I don’t participate in any sort of tournaments.

Oh! I forgot about Hostage Taker. This should be perfect for your strategy.