Deck is designed for post-rotation, so no M13 or Innistrad cards here. Llanowar Elves is a placeholder until Elvish Mystic of M14 comes out.
Unleash Combos
Unleash is a fun mechanic, just significantly unloved, unless it is Rakdos Cackler, the now ubiquitous 2/2 can't block that sees play in every aggro deck running red or black.
Corpsejack Menace doubles the +1/+1 counter you get from unleashing a creature, giving you an even larger creature to turn sideways.
Exava, Rakdos Blood Witch
gives all unleashed creatures haste, already a decent ability to add to your massive creatures.
I got the idea for running these two creatures together from Emrakool's deck Exava's Hasty Hydras!, which takes the +1/+1 counter mechanic to the extremes. While my deck just tries to drop a lot of efficient, hasty threats using unleash, that deck drops hydras of insane power and toughness, sometimes reaching the 100's.
Unleashed Creatures
With Corpsejack Menace and Exava in play, you get some seriously efficient creatures to play at low, low prices.
A special note for Cryptborn Horror. What usually was considered a terrible card is at least significantly better in this deck. After you swing for some damage, you can drop a 16/16 trampling monstrosity or bigger for three mana.
Everything Else
Farseek lets you ramp into the two critical 4-drop creatures that make Unleashed creatures so much better.
Renegade Krasis can boost your unleashed creatures even further when he evolves, which is incredibly easy thanks to Corpsejack Menace giving the double unleash. You can evolve him with even a Rakdos Cackler.
Dreadbore allows you to deal with any threats you opponents play that you can't simply race.
Mutant's Prey is pretty good when every creature you play is guaranteed to be able to have a +1/+1 counter.
Other Notes
When M14 hits, Kalonian Hydra will also probably be ridiculous in this deck. Two of these could sit at the top of the curve, come into play with haste and double all the +1/+1 counters on everything.
