A semi-budget four-color monsters deck centered around green. The deck plays big threat after big threat and backs it up with a few spells. The key difference between this and other Monsters builds is the two Treasure Cruises, which seriously smooth out the lategame.
Play: Ramp into big threats and self-mill to support the Delve cards and Nemesis of Mortals. Basically, this deck goes slightly bigger than what your opponent is trying to do. You want to have several angles of attack and keep deploying huge threats. Save removal for the biggest threats that you can't profitably block.
Mulligans: Make sure that you can reasonably cast something in your hand. Expect to need to mulligan more often than usual, but in this deck, almost any hand where you can cast a threat is a good hand. I'd recommend mulling any hands with one land or less or with no green mana sources. Manadorks are a good plus as well.
Matchups:
Abzan Midrange: If you are the defensive player, prioritize casting Reaper of the Wilds and Arbor Colossus. If you are the aggressive player, prioritize Savage Knuckleblade. Kill Raskshasha Deathdealer whenever they leave it vulnerable, because it's really hard to answer. Sideboard in Treasure Cruise on defense, and always side in color-hate.
Mardu Aggro: Kill Goblin Rabblemaster ASAP. Be careful with activating Monstrous, because Crackling Doom will devour you whole. Sideboard in Barrage of Boulders, Dark Betrayal, and Nylea's Disciple. Save removal for Butcher of the Horde, and don't be afraid to trade your Colossus for it. This deck takes a lot of damage from its lands, so an opportunistic strike can easily win you the game.
Mono-Red/Mono-Black Aggro: Sideboard in Barrage of Boulders and Nylea's Disciple. If mono-black, also side in Dark Betrayal. Kill Rabblemaster. Block stuff. Honestly, straight-up aggro decks are pretty easily beaten by this deck as long as you get to cast your monsters.
G/B Constellation: Enchantment removal is your friend. This is easily one of the toughest matchups, so a lot of the sideboard is hate for it. I'd replace Commune with the Gods with enchantment removal 90% of the time when siding out, as this deck will fill your graveyard plenty fast without it. Game 1 is tough, but a Polis Crusher in the right place can often be fatal. You will be Thoughtseized/Despised/Maggoted a lot, so it will be very hard to bluff.
Temur Aggro: Block the Knuckleblades. You want to be slightly bigger than them. You are the defensive player, no questions there, so sideboard in another Cruise and make sure to kill the big threats. You want to get them to run out of threats before you do.
Jeskai: Oh god, Jeskai. Thankfully, there's not much Jeskai being played right now, but if you do happen to meet a Jeskai, my advice is pretty much: kill Mantis Rider, minimize damage, be bigger.
Heroic: Removal in response is your friend. Also not the most pervasive strategy, but once the rubber hits the road, you will have the bigger threats.
Control: This is your moment to shine and be aggressive. I'd try to go for face as much as possible, but use common sense: when there are 'walkers, kill the 'walkers. Don't overcommit and try to get in and attacking ASAP.
If you have any advice for matchups, please post it in the comments. Thanks!