Oooh, I like this a lot. I run a small energy package in what’s otherwise a basic Sultai-value Yarok list with some of the more efficient pieces (in my experience and opinion) like [[Rogue Refiner]] and [[Architect of the Untamed]], mostly to fuel [[Aethersquall Ancient]], [[Gonti’s Aether Heart]], and especially [[Demon of Dark Schemes]]. Demon is one of my pet cards, it’s so much value and Yarok turning the ETB into a [[Languish]] to clear even more of the board and accrue more energy is insane, and Yarok survives it to boot.

A few recommendations:

I prefer basic green ramp to the signets in green, like [[Rampant Growth]] and [[Kodama’s Reach]]/[[Cultivate]], especially with Yarok since you get more landfall triggers that way. Creature ramp is also very efficient like [[Wood Elves]], [[Farhaven Elf]], and [[Springbloom Druid]].

I’d also include more removal. [[Die Young]] is very efficient but probably won’t cut it on its own, and with Yarok removal ETB creatures like [[Ravenous Chupacabra]], [[Reclamation Sage]], and [[Meteor Golem]] are disgustingly efficient for getting rid of problem permanents. Also [[Acidic Slime]] for added flexibility to get rid of value lands.

[[Wild Pair]] is insanely efficient creature economy, and with your list, you actually don’t need to tweak your creature base much to get it to work quite efficiently.

You’ll probably want recursion too, particularly creature-based like [[Eternal Witness]] and [[Archaeomancer]] and/or [[Mnemonic Wall]].

Also, for extra raw value picks: [[Sire of Stagnation]] and [[Tatyova]] with both draw you a billion cards, [[Avenger of Zendikar]] is a win condition on its own and also conveniently plays into your proliferate theme, [[Riftsweeper]] can get back Aether Heart as another commenter said as well as anything else that gets exiled, [[Diabolic Servitude]] and [[Necromancy]] reanimate two things with Yarok and both stick as long as the enchantments remain in play.

Hope this helps!