I'd put in a slight bit more creature control in the form of more Arrests and Journey to Nowheres. That is if your goal of this deck is to beat down Kuldotha Red and green Infect. However, at least against Kudoltha red, some Spell Pierce would probably work better but you'd have to be able to play first. It seems you don't really have a set idea. I mean I understand the deck is supposed to slap down the early game winners but if you have so many different cards in there you might not get the ones you need when you need them. I'd look at the deck list and figure out what would be good against the fast decks then get playsets of them.
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I'd take out Phyrexian hydra, Blightwidow, Giant Solifuge, Scion, Companion, and Pack leader. Then I'd go with mcphattus' suggestion of the birds and llanowar, 2 Khalni Hydra, and 4 Gaea's Revenge. See how that works out for ya.
I think if I were to change anything in this deck I'd take out two Thruns and add two more fauna shamans. Thrun's a nice enough card but it's a 4 drop for a 4/4. There could be better. In fact I'd probably remove thrun all together, keep the fauna shaman at 2 and run four Gaea's Revenge. A 7 drop 8/5 with haste that cant be countered is a nice way to polish up a game.
I play tested it against a deck with vengevine/elf and it stomped it so idk. The idea is to get them on the defensive from turn 1 and hope for the best. I also had to edit it cause I couldn't find my other guides and I was going to throw in a couple more summons but couldn't find those either