This seems like a really fun take on muldrotha, definitely a spin on what I've been seeing!

Have you considered Final Parting? It’s essentially two tutors in muldrotha

I had Final Parting in initially, but I ended up cutting it for Scapeshift. I'll probably end up trading it back in for Sire of Stagnation.

Also depending on how much of an ass you want to be there are my two favorite cards in my muldrotha deck Contamination and Infernal Darkness. If budget isn’t an issue, Mesmeric Orb is a very nice card that plays with muldrotha very well.

Mesmeric Orb would be a great addition, I'll have to add that one in. Contamination and Darkness are very interesting. They don't quite fit my general playstyle right now, but I might be a bit more sadistic in the future, so I will make sure to keep those in mind.