If you hit Mwonvuli Beast Tracker, you can fetch Stampeding Serow or Stampeding Wildebeests, either of which can repeatedly bounce the Tracker, fetching you a new creature of your choice from 9 mainboard options and an additional 2 sideboard ones for any situation, many of which have ETB effects of their own, so you can bounce them too!
With Arborback Stomper, you get a lot of repeatable lifegain and a serious beater. Kraul Harpooner and Cloudthresher act as serious flyer-hate, and also hit hard. Acidic Slime is great interaction that can be a wincon in blowing up lands. Arbor Colossus is the removal that we can fetch for creatures that don't have flying, but we needed something, and with enough mana it does work. Sentinel Spider is also fetchable, it is an okay blocker. Soul of the Harvests is our fetchable card advantage.
The rest of the deck is a set of ramp-cards, for the fast-toolbox action this deck presents, with Arbor Elf, Elvish Mystic, and Llanowar Elves as our 1-drops, and Wood Elves for additional ramp and bounce-potential. Commune with Nature hits the rest of the deck, except lands, so it is really good. Elvish Visionary is bounce-potential and a cantrip that can get whatever we topped with our tutors immediately. Brutalizer Exarch is our 5-6 Mwonvuli Beast Tracker that can act as non-creature permanent removal with bounce potential.
This is an absurdly budget list, that has serious toolbox potential, and a lot backing it up. It took some time to write up this list, so feel free to upvote it!
Upgrades include Lead the Stampede over Commune with Nature, Primal Command/Eternal Witness over Mwonvuli Beast Tracker/Brutalizer Exarch, and Utopia Sprawl over Llanowar Elves for the Arbor Elf combo, then some switches like Thragtusk over Arborback Stomper (only if you run Primal Command over Mwonvuli Beast Tracker), Beast Whisperer over Soul of the Harvest (only if you run Primal Command over Mwonvuli Beast Tracker), and Nykthos, Shrine to Nyx over some Forests, like 2-3 copies. You can probably run some Dismembers over cards like Kraul Harpooner, Cloudthresher, Arbor Colossus and Sentinel Spider at that point too.
