
Creatures (21)
1 Dragonlord's Servant
2 Atarka Beastbreaker
2 Glade Watcher
2 Colossodon Yearling
2 Hardened Berserker
2 Sabertooth Outrider
1 Summit Prowler
2 Lurking Arynx
2 Stampeding Elk Herd
1 Harbinger of the Hunt
1 Scion of Ugin
2 Savage Ventmaw
1 Dragonloft Idol
Sorceries (5)
1 Roast
1 Epic Confrontation
1 Dragon Fodder
1 Magmatic Chasm
1 Seismic Rupture
Instants (7)
1 Draconic Roar
1 Tread Upon
2 Tail Slash
1 Press the Advantage
2 Sarkhan's Rage
Artifact (1)
1 Atarka Monument
Enchantment (1)
1 Berserkers' Onslaught
Land (25)
1 Evolving Wilds
12 Forest
12 Mountain
Harbinger of the Hunt is one of the better of the five Dragons from the cycle featured in the Intro Packs. His ability to do damage across the board can come mighty in handy when dealing with 1 toughness creatures. In the late game, he can ensure that your forces will be able to overpower your opponents. Since you're going to be running fairly large creatures in a Red/Green aggro strategy anyway, your creatures should be easily able to absorb the damage they would take from the Harbinger's abilities.
Trouble is, the creature line-up in this deck isn't all that impressive., even if its parts look pretty good on their own Atarka Beastbreaker is a fine common creature, though, with the Formidable mechanic. If you have a total power of 8 or more on board, he can gain +4/+4 until end of turn for only 1G. Glade Watcher is a 3/3 with Defender, with the Formidable ability to lose defender until end of turn for 1 Green mana. Colossodon Yearling is a vanilla 2/4 creature.
Hardened Berserker is an odd sort of "ramp" card. Whenever he attacks, the next spell you cast costs 1 colorless mana less. Sabertooth Outrider is a 4/2 that can gain first strike if you can activate Formidable. Summit Prowler is a vanilla 4/3. Lurking Arnyx is a 3/5 that can force a creature to block. Stampeding Elk Herd is a 5/5 that can give all your creatures trample until end of turn if you have Formidable. Scion of Ugin is a colorless Dragon that costs 6 mana and is a 4/4 flyer. Lastly, Dragonloft Idol is a 3/3 for 4 that gains +1/+1, flying and trample if you control a Dragon.
Obviously, Formidable isn't too hard to activate in this deck. But the Beastbreaker is the only creature that really stands out as actually good. The one thing that R/G Aggro decks really need is to stay ahead of the curve, and this deck doesn't really do that at all. Hardened Berserker does help a little bit, but not enough to consistently make any sort of difference.
Also, Formidable can be countered by one of your creatures being destroyed by removal before they can resolve. If you go to activate a Formidable ability, and one of your creatures is meanwhile destroyed, bringing your total power under 8, that ability will fizzle. This probably shouldn't be a huge deal, but it's something to keep in mind.
Non-Creature Spells
The most interesting cards in the deck lie in the non-creature spells. Berserkers' Onslaught is a lesser version of an older card called Rage Reflection. Whereas Rage Reflection gave all of your creatures double strike at all times, for one less mana to cast, Berserker's Onslaught only gives your creatures double strike when they attack. To be fair, this won't matter much of the time, as you don't really want to play conservatively in this type of deck. But it does make a difference.. It's good for an Intro Pack, though.
Roast is a very good removal card, dealing 5 damage to a creature without flying. Dragon Fodder is a card that works well in most red decks, but is awkward as a one-of. Draconic Roar is great if you have a Dragon in hand or one on board. The rest of the non-creature spells are good in a Limited environment, but not really in Constructed.
To say that Dragonlord Atarka would be a good addition to this deck pretty much goes without saying. Atarka has made noise in Standard in the early going and while 7 mana seems like a lot, it's well worth an 8/8 with flying and trample that can take creatures and planeswalkers down upon entering. Surrak the Hunt Caller is easily the best of the Formidable creatures, and being a 5/4, is most likely going to activate Formidable on his own. Giving a creature haste during each of your combats is very powerful and makes cards like Savage Ventmaw and the aforementioned Dragonlord that much more dangerous.
To really get the most out of Formidable, you should perhaps consider Shaman of the Great Hunt and Savage Knuckleblade. You'll have to splash blue to play the Knuckleblade, but both are 4 power creatures that offer great value. The new planeswalker, Sarkhan Unbroken, also helps you gain advantage with extra mana and card draw, but also needs the blue mana. Playing a ramp creature like Rattleclaw Mystic should speed up the deck a bit, too.
The deck could also use more consistent removal and quicker creatures like Flamewake Phoenix. With the Ferocious ability, which only requires you control a creature with power 4 or more, Heir of the Wilds is a much stronger card than Glade Watcher. The only Formidable creatures that will likely remain after changes would be the Beastbreakers and one or two copies of Surrak. Ferocious is a much more consistent ability, but the power of the Beastbreakers can't be overlooked. Also, Atarka's Command is a flexible non-creature spell this deck probably shouldn't go without.
This Intro Pack tries to do something cool. In a casual setting against another Intro Pack, it could hold the line and probably push through a few wins. But it really needs to focus on really being a R/G Aggro deck to succeed. You could also morph this list into a Temur (Red/Green/Blue) deck to really achieve consistent results.