Updated the deck to since the release of Origins.
This is my own take on the current Mono-green aggro decks that have had some recent success. It has a low curve and leverages green devotion to hit hard with Aspect of Hydra.
It has the Deathmist Raptor
+
Den Protector
package, which is just an awesome combo and I don't think I need to explain this.
Avatar of the Resolute is a great two-drop that gives you a 3/2 with reach and trample, with the added bonus of being double green to help pump up Aspect of Hydra.
Reverent Hunter has been replaced with Managorger Hydra. I really feel like it can get bigger than Reverent Hunter, plus it has trample, which is very effective with this deck...no chump blockers.
Surrak, the Hunt Caller has turned out to be a great card. I started with just three of them but they played so well that I just added a fourth. The ideal game goes Turn 1, Elvish Mystic, Turn 2, Avatar of the Resolute, Turn 3, Surrak, triggering formidable and giving itself haste and swinging for 8. Turn 4 can be able anything else, and combined with Aspect of Hydra, swings for big damage.
Boon Satyr fits so well for a number of reasons...you can flash him in, but you can also bestow him on a Den Protector, making the Den Protector a 6/5 (or 7/6 if it's megamorphed) which can only be blocked by something pretty big.
Aspect of Hydra, Become Immense and Titanic Growth are all used to pump and they all work very well.
With Origins released, Nissa, Worldwaker moves back into my sideboard to be brought in against control decks. I discovered playing against Red Aggro is she is great. Even with just 22 lands, 8 of which are fetch lands, I still tend to flood more often than not. Nissa is a great mana dump, creating 4/4 Elementals with trample.
Roar of Challenge works great at clearing all the blockers, and if you force them to block a Deathmist Raptor you can clear out three of their blockers permanently.
This deck measures up well against the Red Aggro decks, especially after sideboarding in Feed the Clan, but they usually bring in Eidolon of the Great Revel, which make my pump spells hurt. Nissa, Worldwaker gives me a way to keep pressure without casting any spells.
The fetch lands provide delve fuel for Become Immense but also help thin the library. I started with just 4 fetch lands, then moved to 6, and finally went to 8 with no adverse effect yet.
SIDEBOARD
A full set of Mistcutter Hydras. I started out with two, but they work so well against U/x Control decks that I added two more.
Roar of Challenge works great at clearing all the blockers, and if you force them to block a Deathmist Raptor you can clear out three of their blockers permanently.
Feed the Clan for some life gain with mono-red. They seemed like a better choice over Nylea's Disciple since they are easier to get into play against mono-red.
Reclamation Sage for some enchantment hate, particularly against Perilous Vault, which is not only painful but exiles the Deathmist Raptors.
With Origins, I've added Setessan Tactics to the sideboard for the mirror...specifically Managorger Hydra. The only way I can counter one that gets big, is to make it fight a Deathmist Raptor.