This is a budget deck. I do think this can be improved with some more expensive cards, but considering this is very budget easy to build, I think it is strong and fun to play.
This deck is a hybrid between aggressive and ramp strategy. This is possible because of Nykthos, combined with the GG creatures in the deck. The plan is to deliver an agressive start and complement that with a couple fatman on the follow.
Some card analisis:
1 mana:Elvish mystic is the only ramp card in the deck, at 1 mana it has an aggressive cost and will payback the mana investment. I would consider experiment one in the slot, it goes great combined with so many 3/x, but that also would make harder for the deck to reach 5 mana.
Aspect of hydra is the only non-creature card of the deck, and the only one worth the maindeck slot so far. Most of the cards have to be permanents, to reach good devotion. So I don't have a lot of room for instants/sorceries. This makes the deck a little predictable, but the raw power is hard to deal with.
2 mana:The core early devotion enablers: Kalonian tusker and swordwise centaur. Emissary is usually better in the 3rt turn, it can be combined with nythos or reverent hunter.
3 mana:boon satyr will almost never surprise/block a 1/1 in standart, by know everybody knows what 3 open green mana means. But that card is still great and budget easy. Helps against mass removal, played eot or bestowed. If you get to 5 mana it can be an awesome pump spell, and 2 count to devotion is nice.
reverent hunter will often come in play as a 5/5, 7/7. Even as 4/4 it is not such a bad deal for 3 mana.
Sometimes, later in game it can get even bigger, like 9/9. This is a great card for devotion decks.
4 mana:I added only 2 copies of Nylea, it can be bad when you get multiple copies. Beside that, this card is simply awesome, a 6/6 trample and pump all in one. Reach 5 devotion is not very difficult for this deck. Against control, it might be nice to hold 1 emissary in hand to improve devotion after the mass removal spell.
5 mana:Arbor Colossus is among the best budget fatties you can get. Ok, he is no Polukranos, but the monster ability is pretty handy sometimes (goodbye desecration demon) and having a 9/9 is not too shabby either. Usually the 1rst dies to removal, but the 2nd stays in game. ;)
x1 mana:Hydra is the best late game spell, in an ideal world, you play this after arbor colossus, sometimes it comes in play 8/8, 9/9 (with haste). I cast it 19/19 once (using 2 nykthos).
I use 4 nykthos because it is such a key card for this deck, I'd rather have 2 in hand than none most of the time.