Im considering taking out the Craterhoof Behemoth's and Hornet Queens, going to 2 of Hooded Hydra and Khalni Hydra, and adding 2 of 3 other hydras, to up the synergy and fatty amount even more. Thoughts?

Vastwood Hydra maybe?

If I do that, I feel like I should add more like Primordial Hydra, Hydra Broodmaster and definitely Kalonian Hydra

Will try.

I'm not a fan of Life's Legacy because you lose a threat and you can be 2 for 1'd by instant speed removal and counter spells. What do you think about Regal Force and Lead the Stampede? Also Garruk Wildspeaker seems a bit better than Nissa since it only costs 4 mana.

@JAIL_HOUSE You can be 2-for-1'd by a counter, but removal won't do it. Sacrificing the creature is part of the cost, which means there's nothing for the removal to be aimed at. It's not a big deal, but I thought I'd mention it.

Nice deck (+1 for you)! Putting 1-2 Nykthos, Shrine to Nyx in the manabase wouldn't hurt considering that it interacts with your Utopia Sprawls and Overgrowths early game, while generating obscene amounts of mana with your fatties once you have them out.

@ Araganor:

You're right about the creature removal. I realised that after I already made the comment. But you still lose a creature to draw. I think there are better draw options available. Now if Life's Legacy was at instant speed it would be awesome for sure.

How about Momentous Fall then? Instant speed, and the lifegain certainly has applications against burn and aggro.

@JAIL_HOUSE, I don't like Regal Force as there's usually not many creatures on the board, except for when you have the tokens (which you won't have without Life's Legacy.I was using Garruk Wildspeaker before Nissa, but I feel that for the 1 extra mana Nissa is way better. I prefer all of Nissa's abilities over Garruks for this deck. I might put in 1 Garruk just so you can have both up?

Considering Lead the Stampede to up the speed.

@Blue_Flame, Definitely considering Nykthos, Shrine to Nyx. I think it would be a great addition! Will try this.

@Araganor, I think having Momentous Fall might be stronger than Life's Legacy, purely because it's instantspeed. 4 CMC is not too bad, and some lifegain never hurts (easily 7+ life this way). Will try this card!

Thanks for your suggestions everyone :D

Mystcutter Hydra is, by far, the best hydra in the game. In conjunction with Kalonian hydra it's STUPID.

Running 2x of each would be great, I think

Might I recommend Khalni Hydra's little brother, Primalcrux

@sir_richard I've had both those hydras in the deck at one point, in my opinion they didn't really fit the deck, felt a bit too slow. There's also almost no synergy with the rest of the deck. I might build a hydra deck at some point though :D

@Signal Pest Interesting, will consider

I like the Hooded Hydra because you get the snakes, helping Khalni Hydra. Wouldn't hurt to consider the Vastwood Hydra either. Gyre Sage might have a home here too if you decide to include them. And my favorite Kalonian Hydra

Hyras are my favorite. I've been looking for a decent deck for one for a while. Def. Plus 1 from me.

@sir_richard @doctorsmegma so I ended up taking out the Genesis Waves. I don't think those were that good, considering it's only really worth it with 11+ mana to grab Craterhoof/Khalni, which means it's actually quite slow. Instead I added in Mistcutters and a Kalonian. They seem pretty strong in this deck, but don't combo that well with the deck. I'm still open to switching those out for something else.

I've actually been messing around with this For a few days and I've though about including Hydra Broodmaster in collaboration with Kalonian Hydra. Broodmaster doesn't have trample, though. But, the extra tokens can really help with Craterhoof Behemoth So I'm on the fence about it. Like I said, I Dig hydras. So that's my goal. I don't know if you'd agree, but I've been testing it. I'll probably throw in Mistcutter Hydra too. I'll probably keep Genesis Wave and use Progenitus if I really want to go tribal. But ywhat you have built so far is super prestine and the synergy is great. I'm just too experimental for my own good.

Gaea's Revenge could be a good 1 spot in the deck for those control matchups.

and Avoid Fate is an underused SB option

Instead of Surrak, the Hunt Caller you should use Xenagos, God of Revels cause it give Emrakul, the Aeons Torn haste like Surrak, the Hunt Caller but it also give it +15/+15

@doctorsmegma I'm considering Broodmaster instead of Mistcutter. It might be better for the deck, although slower.

@Caligula Avoid Fate is definitely better than Guttural Response, thanks! Sideboarded this. Oh and Gaea seems very good against all kinds of control but I'm clueless as to what I could take out for it. Sideboarding it doesn't feel right.

@Awesomenator33 I know about that card, but it means you need to either: Splash in red or use utopia sprawl for red. If you don't you can only play it with Tooth and Nail. Being able to play it from your hand is great because it works for a ton of situations, not just tooth and nail. Besides, if you're using tooth and nail for Emrakul + Surrak, almost always you've already won. No need for the +15+15. Thing is, I don't want to splash red just for this as it doesn't work with Arbor Elf nor Nissa, Worldwaker. Using sprawls for it? -eh. If it didn't need any red, this would be an easy choice ofcourse as Xenagos is just way way better. I'm open to ideas for possibly turning this into a GR deck, but I don't think it'll improve much that way.

This deck is the real deal... I can't see any defense against flying creatures, so Affinity might just smash you into the ground before you can take off (the odds of winning before Affinity does with this deck aren't quite high enough, I'd guess), but other than that, the power level is amazing.

In terms of improvements, I can think of Vines of Vastwood only - it's a great offensive and defensive card with an insane power level (as you can cast it on creatures your opponents control to pseudo-counter their spells and abilities) all for one mana, and it seems to be a great replacement for at least 2 of your Avoid Fates in the sideboard.

Good luck with this deck!

@BlueScope Interesting. Vines of Vastwood does seem good, but did you take into account that Avoid Fate can also save Garruk/Nissa/Utopia Sprawl/Overgrowth? If no, do you still think I should put in Vines? I'm not sure if it weighs up.

Also, I'm considering to throw out all Kalonian Hydra and Mistcutter Hydra. I mean they're pretty good, but not amazing. I'm thinking I might add in some more token creators just to up the speed and synergy even more. @BlueScope specifically, I'm thinking of Hornet Queen which locks the board VERY nicely (Deathtouch), synergizes amazingly well with Khalni Hydra and Craterhoof Behemoth and it would win against any flyer (affinity) deck. Opinions?

Thanks for the suggestions everyone!

I did consider that Avoid Fate saves all permanents, but even in a post-board match, I wouldn't want to be defensive with green. Vines seems to be a good balance between saving your permanents and having the chance of sneaking another 4 damage in on an unblocked creature (possibly one you save from getting Lightning Bolted at the same time). You should've long overrun the opponent before destroying planeswalkers with spells becomes all that relevant (and even then, getting a Hero's Downfall out of them for a net loss of two to three mana that could've otherwise killed your Khalni Hydra is easily feasible, if you ask me).
Actually, what I considered the major downside of switching Avoid Fate to Vines was that you couldn't protect your enchanted lands (not that land destruction is big in modern, but it IS a weakness in this deck).

I like Hornet Queen over Kalonian Hydra a lot, but I'm a fan of Mistcutter Hydra (not only against blue), simply because a hastey creature isn't what I'd expect a lot coming from green, and you're capable of producing a 10/10 and upwards thread with haste that scales very nicely. The lack of evasion keeps it from being a real win condition against everything that isn't Tron or Storm, so maybe Hornets are the better choice... hard to say. In the end, seeing two Hornet Queens in the list would be great, so maybe trade one Mistcutter Hydra?

As for the sideboard, I wouldn't play 3 Blood Moons. You don't have all that many means of producing red mana, and the chances of them sitting on your hand if you play 3 of them seems too high. 1 or 2 should do (but I have to say, I like the inclusion of it in general :) )

@BlueScope solid reasoning, I have to agree with you on almost everything.

I don't like having 1 of a card in the deck, unless it is essential (like Surrak), because it lowers the consistency in the deck. I mean sure, once every now and then the Mistcutter might give you the win, but generally so will the other cards, right? I think I'd rather have a higher consistency (and for example play 1 more Wolfbriar Elemental). This is also reason why I want to take out the Kalonian. Again, I'm not sure though. Thanks for deckbrewing with me!

I think the sideboard def. Needs Avoid Fate and Gaea's Revenge. I'd swap out Kalonian Hydra and /or Hornet Queen because control matchups don't need 1/1 deathtouch tokens really. Vines of Vastwood and Dismember is a must and Apostle's Blessing could be helpful too. Basically you don't want to lose your ramp so protecting Arbor Elf and Voyaging Satyr is important for burn. With the possibility for so much ramp, you need to protect yourself too so you can actually resolve big creatures, ramp creatures and important enchantments. I also think having Nissa and Garruk is a bit overkill so side boarding them out in burn/control matches is an option. I also like Wild Defiance Feed the Clan for burn matchups too... And dare I say a copy of Fog