Updated Tier 10 set bonuses

Death Knight

• 2 Pieces (DPS): (NEW)Your Obliterate and Scourge Strike abilities deal 10% increased damage., and your Heart Strike ability deals 7% increased damage.

• 4 Pieces (DPS): Whenever all your runes are on cooldown, you gain 3% increased damage done with weapons, spells, and abilities for the next 15 second.

• 2 Pieces (Tank): Increases the damage done by your Death and Decay ability by 20%.

• 4 Pieces (Tank): When you activate Blood Tap, you gain 12% damage reduction from all attacks for 10 seconds.

Druid

• 2 Pieces (Balance): (NEW) When you gain Clearcasting from your Omen of Clarity talent, you deal 15% additional Nature and Arcane damage for 6 seconds.

• 4 Pieces (Balance): (NEW) Your critical strikes from Starfire and Wrath cause the target languish for an additional 5% of your spell’s damage over 4 seconds.

• 2 Pieces (Restoration): The healing granted by your Wild Growth spell reduces 0% less over time.

• 4 Pieces (Restoration): Each time your Rejuvenation spell heals a target, it has a 2% chance to jump to a new target at full duration.

• 2 Pieces (Feral): Your Swipe (Bear) and Lacerate abilities deal 20% additional damage and the cost of your Rip ability is reduced by 10 energy.

• 4 Pieces (Feral): 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

Hunter

• 2 Pieces: Your Auto Shots have a 5% chance to cause you and your pet to deal 15% additional damage for until cancelled.

• 4 Pieces: (NEW) When your Viper Sting, Serpent Sting, and Wyvern Sting abilities deal damage, you have a 5% chance to gain 20% attack power for 10 seconds.

Mage

• 2 Pieces: (NEW) Your Hot Streak, Missile Barrage, and Brain Freeze talents also grant you 12% haste for 5 seconds when the effect of the talent is consumed.

• 4 Pieces: (NEW) Your Mirror Image ability also causes you to deal 18% additional damage for 30 seconds.

Paladin

• 2 Pieces (Retribution): (NEW) Your melee attacks have a 40% chance to reset the cooldown on your Divine Storm ability.

• 4 Pieces (Retribution): (NEW) Your Seals and Judgements deal 10% additional damage.

• 2 Pieces (Holy): The cooldown on your Divine Favor talent is reduced by 60 sec.

• 4 Pieces (Holy): (NEW)While your Divine Illumination talent is active, your healing spells are increased by 35%.

• 2 Pieces (Protection): Your Hammer of the Righteous ability deals 20% increased damage.

• 4 Pieces (Protection): When you activate Divine Plea, you gain 12% dodge for 10 seconds.

Priest

• 2 Pieces (Shadow): (NEW) The critical strike chance of your Shadow Word: Pain, Devouring Plague, and Vampiric Touch spells is increased by 5%.

• 4 Pieces (Shadow): (NEW) Reduces the channel duration and period of your Mind Flay spell by 0.5 seconds.

• 2 Pieces (Healing): (NEW)Your Flash Heal critical strikes cause the target to heal for 25% of the healed amount over 9 sec.

• 4 Pieces (Healing): (NEW)Your Circle of Healing and Penance spells have a 20% chance to cause your next Flash Heal cast within 6 sec to reset the cooldown on your Circle of Healing and Penance spells.

Rogue

• 2 Pieces: (NEW) Your Tricks of the Trade ability now grants you 15 energy instead of costing energy.

• 4 Pieces: (NEW) Gives your melee finishing moves a 13% chance to add 3 combo points to your target.

Shaman

• 2 Pieces (Enhancement): When you activate your Shamanistic Rage ability you also deal 12% additional damage for 15 second.

• 4 Pieces (Enhancement): Each time the beneficial effect of your Maelstrom Weapon talent reaches 5 charges, you have a 15% chance to gain 20% attack power for 10 second.

• 2 Pieces (Elemental): Your Lightning Bolt spell reduces the remaining cooldown on your Elemental Mastery talent by 1 second.

• 4 Pieces (Elemental): (NEW) The cooldown on your Lava Burst ability is reduced by 1.5 seconds.

• 2 Pieces (Restoration): Your Riptide spell grants 20% spell haste for your next spellcast.

• 4 Pieces (Restoration): Your Chain Heal critical strikes cause the target to heal for 25% of the healed amount.

Warlock

• 2 Pieces: (NEW) The critical strike chance of your Shadowbolt, Incinerate, Soulfire, and Corruption spells is increased by 5%.

• 4 Pieces: (NEW) Each time your Immolate and Unstable Affliction spells deal periodic damage, you have a 15% chance to gain 10% damage done by you and your pet for 10 seconds.

Warrior

• 2 Pieces (DPS): (NEW) When your Deep Wounds ability deals damage you have a 3% chance to gain 20% attack power for 10 seconds.

• 4 Pieces (DPS): (NEW) You have a 30% chance for your Bloodsurge and Sudden Death talents to grant 2 charges of their effect instead of 1, reduce the global cooldown on Execute or Slam by 0.5 seconds, and for the duration of the effect to be increased by 100%.

• 2 Pieces (Protection): Your Shield Slam and Shockwave abilities deal 20% increased damage.

• 4 Pieces (Protection): Your Bloodrage ability no longer costs health to use, and now causes you to absorb damage equal to 20% of your maximum health.

(Source)