Bogle Progenitus Mutate

With this deck you want to mutate to trigger ramp, disruption, card draw, wheel effects and buff your creature you're mutating onto. One of the upsides when playing only creatures and lands, is, that Thalia, Guardian of Thraben doesn't work against us at all, making Humans and Death & Taxes worse against us.
Another nice thing is that we can play Umori, the Collector as a companion, which isn't really important for our strategy but maybe nice to have in some matches. We could easily play the list without him and nothing would change.

The greatest weakness of Simic Mutate is, that targeted removal really messes us up, so we put Bogle, and it's less popular brother, Gladecover Scout, in there. Now only board wipes can harm our mutating monsters.

For the mutating creatures in the deck we have ramp with Migratory Greathorn, disruption with Pouncing Shoreshark and to punish our opponents for not being able to deal with hexproof mutating bogles, we have Glowstone Recluse to make our stuff enormous. We have a playset of Auspicious Starrix, which is going to wheel a lot in the late game. I often see mutate decks being played with Starrix but no real stuff to hit with it, so I first put Emrakul, the Aeons Torn in there, but as I wanted to keep the list a bit budget and the opponent would in theory still be able to deal with Emrakul, I put Progenitus in there instead. As he has protection from everything the opponent can't do anything against him and we have basically won. I like how it's totally inpracticable, as we have no way of actually casting it, but just having that as an absolute finisher adds a nice smell of jank to the list.

For ramp we have Elvish Mystic and Pollywog Symbiote. Pollywog Symbiote is a perfect fit for the deck, as it can discard our uncastable Progenitus and draws cards, while cheating mana. Umori, the Collector technically is also ramp but will only be played so late that it will probably have no real impact.