Deck in progress. So far, it works like this:

Start: Ideally, I want to start the game with 2 or more lands, and with 2+ of any mana "helpers" (Elvish Mystic, Llanowar Elves, Font of Fertility and/or Ilysian Caryatid). Elvish Mystic, Llanowar Elves and Font of Fertility is a great way to get something into play on turn one. Ilysian Caryatid and Font of Fertility serves as mana "helpers", but as well as getting access to at least 1 Mountain land / red mana (more on that later).

Mid: After I have (hopefully) managed to get a lead in regards to mana, I want to look out for either Hooded Hydra or Savageborn Hydra, where the Savageborn Hydra needs at least 1 Mountain / red mana to be summoned. Luckily, his ability can be paid by either a red or green mana, so if I lose a Ilysian Caryatid, and I don't have a Mountain, I will be good as long as I got it into play before that.
Hooded Hydra can be summoned faced down for 3 mana as a 2/2 creature, and be Morphed by paying 5 mana, giving it +5/+5 counters, which can be a cheap way to get a strong 5/5 creature instead of summoning it normally and having to pay 7 mana for the same power/toughness.
Savageborn Hydra is really strong, and can get really strong if I keep boosting its power (2 mana for +1/+1 counters, no tapping needed). Not only that, but it also has Double Strike, hitting for double damage on the opponent if not blocked or handled with.
If I don't have these in my hand, I have Uncage the Mangerie to help me get them (4 mana for 1 Hooded Hydra and 1 Savage Hydra to my hand, as X count as 0).

Late: As Hooded Hydra and/or Savageborn Hydra has started to harass the battlefield, I will try to get the rest of my creatures into there as well. With Nylea I can give all my creatures trample, Gargoz can help me get the rest of my Hooded and Savage Hydra's out there with the rest, and Kalonian Hydra will let me double everyones counters with each attack (insane).
To help me get a hold of some of these, I've added Shared Summons, which lets me place 2 creatures from my library into my hands.
I've also added Trollhide to help me attack with Kalonian Hydra every turn, not being afraid to lose him due to Regenerate.
Nyktos can help me reach insane mana levels if I manage to get all my creatures out on the battlefield due to devotion.

Extra: These are some of the cards I added that doesn't necessarily synergise with the rest, but can be pretty important late game if I play against a certain deck. I added Wildest Dreams to be able to summon a lot of cards back to my hand later in the game, when mana shouldn't be an issue anymore. This can help me withstand a mill deck, as well as retrieving my bombs if I lose them (mainly Kalonian).
Feed the Clan is pretty much only necessary against aggro decks. I have played with similar decks before, and decks like this can struggle against decks that chips away your health early when you don't have much defence, making it easy to kill you if they can get a spell or unblockable creature to get past your late game defence. With Feed the Clan, I can quickly get back to (or nearly) full health again, giving me more time to deliver a fatal blow.

Sidebord: This is not complete, but I think I'm going to add 2 extra Feed the Clan for heavy aggro decks, 4 Steelbane Hydra's to deal with enchantment/artifact decks and 4 Mistcutter Hydra's if I play against a blue control deck.

Feel free to give me some feedback! I do not have any experience playing competitively, and have only been playing for fun with friends.