Ans seeing the number of permament I got in my deck... Changing Muldrtha for Biogenic Ooze can really be a thing !
I'll try it right now.
As you imagined, average can be tough against Big white or Big red, and I often sacrifice my Vraska 4, just to kill one thing. I don't hesitate to use Keasis for 4 mana as well. You don't care because you cycle a lot.
Assassin's trophy is not a card I love because it gives a land advantage to the opponent, but it kills a permanent. Awfully efficient for 2!
Muldrotha is the last add to this deck, it's a plus, but not needed to win. Someone said me to change for Limons due to wilderness use!
I could see it working really well into the end game with Muldrotha, but your average seems a little high. How has it fared so far with playing it? I forgot about Assassin's Trophy. May have to consider using it.