Big Green.Mono color decks are only getting better when KTK releases. I don't have to worry about having 3 colors, or how to fix my mana base for it. It's hard to get screwed by land, which is one of the biggest weaknesses of a 3 color deck in 60 cards.
Mainboard choices and why:
Arbor Colossus: I feel this card is just default if you go big green. 6/6 for 5 is what green wants, it has reach (which isn't too relevant), but most importantly gives 3 devotion. And people say he's got a nice butt, so I guess there's that.
Bow of Nylea: Eh, kinda threw it in there. It doesn't do anything well, but it does a lot of things. Nice utility. The deathtouch is irrelevant, since I don't have to worry about ever trading up.
Courser of Kruphix: This isn't the best green card, and one of the best cards in any color in standard for no reason. Helps you dig through your deck, blocks well, gives you life, and 2 devotion.
Elvish Mystic: Elvish Mystic.
Genesis Hydra: If I draw him early, I'll likely win. If I draw him late, I'm going to win. Genesis Hydra is not only just Genesis Wave on a stick, but on a multi-headed stick that doesn't need to be weak.
Hooded Hydra: Get big, do damage, leave dudes when he eats Hero's Downfall. I've yet to actually morph him a single time in testing, but I guess that may be relevant at some point to someone in some game.
Hornet Queen: I had my doubts. I did. I didn't like this card. "A 7 cmc 2/2 deathtouch flyer? You gotta be kidding me. Who cares if it makes a bunch of 1/1 flying deathtouch tokens?" I have since eaten those words, regurgitated them, then ate them again.
Nissa, Worldwaker: Utility. Createing manlands can be very helpful, but untapping 4 forests is better. If I get her ult off and have a Genesis Hydra in my hand, oh boy oh boy oh boy.
Nykthos, Shrine to Nyx: Mono green. X creatures. Lots of multi green in cmc.
Nylea, God of the Hunt: Always online, but is really just an indestructable enchantment that gives everything trample.
Polukranos, World Eater: My favorite green card in standard. He bounces into the club early, then when you feed him enough he hits on (he actually hits them) all the ladies. Or a single lady. This causes them to enrage, slapping him down. This leaves his bros to do whatever they want. Perfect wingman.
Reverent Hunter: Why not.
Sylvan Caryatid A mana dork that can block.
Sideboard:
Mistcutter Hydra: Get big, hates blue, comes out at any point when he's needed. Allstar sideboard card.
Naturalize: When you absolutely want that Ascendency/Banner/Bestow dead.
Nessian Demolok: I love this card. I know Tribute is generally considered a bad mechanic, and it is on most cards, this is one of the ones that it actually works on. His body is fine if tribute is paid, nothing to write home about. But if it isn't paid, I get to kill something very important. Playing against a 3 color deck and they only have one land that can produce one of their colors? Perfect. Planeswalker? Perfect. But they can't ignore a 6/6 either.
Nylea's Disciple: Comes in against burn. One decent Disciple heal can shut down a burn deck, two will put them so far behind that it won't matter.
Unravel the Aether: Gods. And Sultai.
