Deck built around swarming the enemy, with synergies built around the minions.
Has been built using only free cards(from this pool http://www.hearthpwn.com/cards?filter-set=2&display=1)
To swarm the board with many minions
Very good card even without its battlecry, can be extremly powerfull against any deck built around weapons(afak those decks are top tier)
To protect other weak and important minions as well as keeping hero safe in later stages of the game
Buffs to deal more damage with minions to the enemy, Blessing of Kings also should take care of keeping alive important minions
For board control
Cards that syregizes well with that deck. I like to call Raid Leader a small Savage Roar in Paladin deck. Frostwolf warlord gets bigger for every other friendly minion, this also counts Hero Power ones. Stormwind Champion is a "big bomb" late game card, also buffing other friendly minions
A little draw power.