You need more ramp, so try adding Birds of Paradise or Sylvan Caryatid . Arbor Elf isn't going to do much alone.
Also, you really need Karametra's Acolyte + Staff of Domination , and switch out Magus of the Candelabra for the Acolyte.

I also have a few questions:

• How competive does your deck want to be?
• Do you want to add in blue, to make more options?
• Have you thought about using +1/+1 enchantments like Doubling Season or Hardened Scales for more counters?

Finally, you really need to protect yourself from board wipes!

Very good points! Thanks for the comment. To the questions, yes, I do want this to be fairly competitive. I have thought about and tested out splashing blue or white or even red to allow for more options, but I've never found something that doesn't begin taking away from the main theme. I've thought about having +1/+1 enchantments, but at that point I think a higher priority would be to add a protective enchantment in something like Asceticism or Privileged Position . I do agree with having more ramp, and I thought about switching out the Magus of the Candelabra for 2 more Garruk Wildspeaker . However, I do like the Sylvan Caryatid a lot. Maybe because of the theme, Karametra's Acolyte would even be a better option. I used to run them in here but took them out. I think Staff of Domination could add potentially an infinite amount of mana, but my only worry is that at that point, what will I spend it on? I've run into having far more mana available than needed many times with this deck. I think what I'll do is switch 2x Magus for 2x Acolyte. I would love to throw in one of the two hexproof enchantments I mentioned, but I'm just not sure what to take out at this point. I did have to throw in Hunter's Insight just because the card draw is so needed so badly.

Thanks so much for the advice! I'll make the initial changes then I'd love to hear more advice based on my answers to those questions!

Infinite mana on Polukranos! Or Vastwood Hydra ftw!
Anyway, maybe Primal Rage for the trample, or Rogue's Passage for unblockable?

I do already get trample on Primalcrux and Kalonian Hydra . And Nylea, God of the Hunt and Garruk Wildspeaker give trample to everything. But, I do really want to put at least one Vastwood Hydra in the deck. I'm just not sure what to take out honestly. Maybe I'll take 1 Aspect of Hydra out and 1 Kalonian Hydra out but I don't know. They both seem so crucial. Any suggestions on what to take out? I really just need to make space for these things because I also wanted to put in something like Asceticism or Privileged Position into the deck.

Maybe take out an Ooze or Hunter? It won't be necessary to have 4, as it will hurt your curve.
And add more ramp! Maybe have Search for Tomorrow instead of Overgrowth?
Is your deck on a budget?

Okay, So I took out 1 Kalonian Hydra , 1 Predator Ooze , 1 Aspect of Hydra , and 1 Mosswort Bridge to add 2 Vastwood Hydra and 2 Asceticism . And no, it isn't on any kind of budget! So welcome any kind of expensive additions if they are truly better and needed. I think in terms of ramping, I've got things covered in the ramping section of the description.

If it's counters you're looking for, then Increasing Savagery is a great way to get a ton on the board.

Good point! I decided that the 2x Asceticism can be on sideboard to swap in 2x Increasing Savagery . I think I ought to almost always have enough mana mid-game to play it and then play its flashback.

Primordial Hydra instead of 1x Geist and 1x Vastwood Hydra?