It was the plane that gave us Glimpse of Nature, so theres still hope
Due to the way this ability is worded, milling several creatures at once only generates one zombie, so Sidisi decks often want to be filled with creatures and means of repeatedly milling small numbers of cards to make an enormous zombie horde
They are not the best decks in format but the difference between a deck built from what you happen to have and an "optimal" deck (if that's even a thing in this format) are way smaller than in Standard or Expanded formats
13 Bubbling Muck Get That Mana Now A slightly limiting card but one with plenty of potential, Bubbling Muck is a one-mana sorcery from Urza's Destiny that can turn a few mana into tons
All that remains is to consider how to play against more frequent static interaction
Soft buyouts, where a few buyers collectively purchase large quantities of a specific card, can temporarily spike prices