Mowu, Goodest of Boys

AwU, what's this? It's Mowu, the most loyal and beautiful companion the world has ever seen! This deck is all about counters, counter, counters (the +1/+1 kind)! Together with a solid monogreen-stompy shell, the objective of this deck is to get on the board early with our commander, beef him up full of +1/+1 counters, and smash face as often as possible! The deck fluctuates between the full-on-aggro to the somewhat midrange-y, but the idea is always the same: play a sizeable dude, get him bigger, and smash face!

This deck is a lot like a monogreen stompy deck, say with Yorvo, Lord of Garenbrig or Questing Beast as the commander. The difference here is that we replaced a lot of the good green creature top-end with a lot of spells and creatures that give +1/+1 counters to our good boy! It's totally worth it, just look at his face! He loves it :)

The Ramp:

Oh yeah baby, we are doing the Leyline of Abundance thing again! We have 5 creatures that tap for mana to go with it, and Nissa, Who Shakes the World to make all our forests tap for 3 if it's all on the board! It's ambitious as hell but with all this mana potential we might be able to actually activate it rather early, allowing us to grow our entire board and our good boy to keep beefing up. Also, Nissa is just a busted card and if this deck wants to win it needs to run SOME busted stuff (more on a few of those later). We also run one Arcane Signet for extra fast mana and one Beanstalk Giant to get a land in plan and just be a big beater on its own.

The Beaters:

This deck's win condition is combat damage. Whether it's 25 points or more, we win by hitting them square in the face a few times with our enormous creatures. All of these creatures are either quite powerful on their own or synergize with our proliferate spells. We start off with Pelt Collector as a one-drop that can drow to gargantuan stature if left unchecked. Wildborn Preserver needs a bit more of a mana incentive to start growing, but can become huge after just a few turns. Barkhide Troll has amazing synergy with our +1/+1 counters, as we can keep him growing and, as long as we have 1 mana left up, he will never be targetable. At the 3-cost slot we run Lovestruck Beast and Yorvo, Lord of Garenbrig, both of which serve as powerful threats, and lower the cost of The Great Henge later. Questing Beast is just the best green creature out there right now, and since we can keep it growing, it's a pretty safe bet that no planeswalker will be left on the board against it. As a later-game threat we run Biogenic Ooze, which can be a fantastic mana sink in case we don't find more threats to put on the board, and can be proliferated to high heavens. We also run 4 of the "X-cost" creatures in Voracious Hydra, Steelbane Hydra, Stonecoil Serpent, and Ugin's Conjurant. All of these are flexible creatures that have some other form of upside in our deck, and all can make good use of the +1/+1 counters we can give them.

Counting it Up:

 Our commander is hungry for counters, and we need to feed the good boy! We have one cheeky Stony Strength as a 'combat trick', or to give a huge mana boost to our Incubation Druid. Pollenbright Druid is usually a card we want to proliferate with, but can just add two counters to Mowu if necessary. Evolution Sage is a powerful threat if left unchecked, and will be adding counters to all of our things extremely fast. Jiang Yanggu, Wildcrafter is a) flavorful b) another source of ramp and c) a consistent way to add +1/+1 counters to Mowu, so he's a no-brainer in this deck. We also run one Weapon Rack, which is hilariously effective in this deck, possibly adding 6 counters to Mowu at least, as it can also be proliferated. We run two Viviens, and I bet you didn't even know Vivien, Nature's Avenger was a thing. This card seems like a meme at first, as six mana is a huge ask, but adding 3 counters to one creature for her +1, as well as letting us grab the first creature at the top of our deck for her -1 made her surprisingly effective in this deck. We also run Vivien, Arkbow Ranger for her extremely powerful abilities and lower mana cost, as she is really a superior version. Finally, we run two rather expensive spells in Biogenic Upgrade and Planewide Celebration to make our creatures absolutely massive for a bursty finish.

Drawing them Cards:

Wait a minute, those cards are banned! Call the cops, we are playing Veil of Summer and Once Upon a Time. More than a meme in this deck, Veil of Summer is actually quite useful, as our strategy is to just play big dudes and hope our opponent doesn't interact with them. Once Upon a Time is a way to help us find another one of our mana dorks early on, or simply dig for creatures later on, which is usually what we are looking for. We run Beast Whisperer to draw a card whenever we cast a creature and Guardian Project and The Great Henge to draw every time they enter the battlefield. The Great Henge should be rather easy to cast in this deck that keeps growing its creatures, and has pretty stellar synergy with our commander and proliferate spells. Finally, we run one Return of the Wildspeaker to draw an obscene amount of cards for a green deck with our enormous creatures.

Lands:

The lands for this deck are pretty simple: 16 Forests, one Gingerbread Cabin, one Fabled Passage, and one Castle Garenbrig give us 19 Green sources, giving us 5 other slots to get some extra value out of our lands. The most powerful of the bunc are Karn's Bastion to just proliferate everything and Blast Zone, which is one of the few ways this deck has to remove certain permanents. We also run one Cryptic Caves because the deck stalls a bit, one Emergence Zone to let us get tricky with our spells if we have a lot of mana, and one Mobilized District to add to our board, and maybe also give some counters for a very powerful man-land-threat.

Have fun, and remember to ALWAYS pet the dog.