Death Knight
2P Bonus - Increases the damage done by your Death and Decay ability by 20%.
4P Bonus - When you activate Blood Tap, you gain 12% damage reduction from all attacks for 10 sec.

Druid
2P Bonus - Your Swipe (Bear) and Lacerate abilities deal 20% additional damage and the cost of your Rip ability is reduced by 10 energy.
4P Bonus - Your Enrage ability no longer decreases your armor and instead decreases all damage taken by 12%, and the periodic damage done by your Rake ability can now be a critical strike.

Paladin
2P Bonus - Your Hammer of the Righteous ability deals 20% increased damage.
4P Bonus - When you activate Divine Plea, you gain 12% dodge for 10 sec.

Warrior
2P Bonus - Your Shield Slam and Shockwave abilities deal 20% increased damage.
4P Bonus - Your Bloodrage ability no longer costs health to use, and now causes you to absorb damage equal to 20% of your maximum health. Lasts until cancelled.