Hydras! The goal is to ramp into Hydras. Ideally, the deck wants to ramp into turn 3 Polukranos or Kalonian. then keep dropping Hydras for the rest of the game, eventually abusing Nykthos and devotion to feed their abilities.
Elvish Mystic: Turn 1 mana dork to speed up the deck
Sylvan Caryatid: Turn 2 mana dork that has good toughness and hard to kill.
Courser of Kruphix: He's here in case T3 Polly or Kalonian doesn't happen. Has good toughness to protect you and helps thin out your deck while gaining you life.
Chord of Calling: Instant speed creature fetch. Need I say more?
Mistcutter Hydra: He's a solid Hydra with haste, To make things even better, he screws over blue decks.
Genesis Hydra: 2-for-1 that you'll usually want to pump at least 4 mana into X (can be done as early as turn 3, with good ramp). This way, he may be able to fetch Nylea, Polly, Kalonian or even Broodmaster if enough mana is paid.At worst, you'll get Courser or a mana dork.
Polukranos, World Eater This guy needs no introduction. Big stompy 5/5 for 4 mana that threatens to remove your opponents creatures while getting bigger.
Kalonian Hydra: This guy alone will win you the game if he's not dealt with quickly. Team him up with other Hydras and he's even deadlier.
Hydra Broodmaster: Pumps himself up and makes more Hydras, helping you beat opponents late game.
Nykthos, Shrine to Nyx While not devotion based, the deck has plenty of green symbols on it's stuff to make good use of Nykthos, especially for Polly and Broodmaster's abilities.
Forest Can't play the deck without these.
Chord of Calling
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Nylea, God of the Hunt
: Chord of Calling into a Nylea during combat allows you to add trample to your creatures as a combat trick and gives you a 6/6 Indestructible.
Chord of Calling
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Kalonian Hydra
: Chording into a Kalonian Hydra at your opponents EOT allows you to attack with it your other hydras on your following turn, doubling all of their counters, increasing your tempo and potentially winning the game.
Kalonian Hydra
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Mistcutter Hydra
: Kalonian followed by a Mistcutter on the following turn can be devastating, At minimum, Mistcutter will drop as a 4/4, then immediately become an 8/8 when it attacks with Kalonian. That's 16 damage as early as turn 4,
Any suggestions are welcome as I'm always trying to improve my decks. Any help making the deck faster is welcome. When Khans comes out, Kalonian will rotate and any help deciding what to replace him with will be helpful. Heroes' Bane is similar, but not as powerful. Perhaps making the deck Simic and filling the 5 slot with Prophet of Kruphix for the tempo increase and Kruphix, God of Horizons for the ability to keep my mana wouldn't hurt either. Let me know what you guys think.