AS NEW GEAR BECOMES AVAILABLE, I'VE COMPILED A LIST OF YOUR TIER 15 SET BONUSES. IF YOU SEE A MISTAKE PLEASE CORRECT ME. SEE CLASS CHANGELOGS ON wowhead.com

Death Knight





Death Knight T15 Blood 2P Bonus: Removes the rune cost of your rune tap ability.
Death Knight T15 Blood 4P Bonus: Your Bone Shield ability grants you 15 Runic Power each time one of its charges is consumed.
Death Knight T15 DPS 2P Bonus: Your attacks have a chance to raise the spirit of a fallen Zandalari as your Death Knight minion for 15 sec. (Approx. 1.15 procs per minute)
Death Knight T15 DPS 4P Bonus: Your Soul Reaper ability now deals additional Shadow damage to targets below 45% instead of below 35%. Additionally, Killing Machine now also increases the critical strike chance of Soul Reaper.



Druid




Druid T15 Balance 2P Bonus: Increases the critical strike chance of Starsurge by 10%.
Druid T15 Balance 4P Bonus: Nature's Grace now also grants 1000 critical strike and 1000 mastery for its duration.
Druid T15 Feral 2P Bonus: Gives your finishing moves a 15% chance per combo point to add a combo point to your target.
Druid T15 Feral 4P Bonus: After using Tiger's Fury, you gain 40% increased critical strike chance on the next 3 uses of Mangle, Shred, or Ferocious Bite.
Druid T15 Guardian 2P Bonus: Each attack you dodge while Savage Defense is active increases the healing from your next Frenzied Regeneration within 10 sec by 10%, stacking up to 10 times.
Druid T15 Guardian 4P Bonus: You generate 50% more Rage from your attacks while Enrage is active.
Druid T15 Restoration 2P Bonus: Swiftmend’s ground effect can now heal up to 4 targets each time it heals.
Druid T15 Restoration 4P Bonus: The healing done by your Rejuvenation increases by 6% each time it causes healing.


Hunter





Hunter T15 2P Bonus: Your Steady Shot and Cobra Shot have a chance to summon a Thunderhawk to figth for you for the next 10 sec. (Approx. 1.00 procs per minute)
Hunter T15 4P Bonus: Your Arcane Shot and Multi-shot have a chance to trigger a Lightning Arrow at the target, dealing 100% weapon damage as nature.(Approx. 3.00 procs per minute)


Mage





Mage T15 2P Bonus: When Alter Time expires, you gain 1800 Haste, Crit, and Mastery for 30 sec.
Mage T15 4P Bonus: Increases the effects of Arcane Charges by 5%, increases the critical strike chance of Pyroblast by 5%, and increases the chance for your Frostbolt to trigger Fingers of Frost by an additional 6%..


Monk





Monk T15 Brewmaster 2P Bonus: After Elusive Brew expires, the amount of damage you Stagger is increased by 12%. This effect lasts 1 sec per stack of Elusive Brew consumed.
Monk T15 Brewmaster 4P Bonus: Each time you take damage from Stagger, you have a 10% chance to make your next Purifying Brew cost no Chi.
Monk T15 Mistweaver 2P Bonus: Your Renewing Mist heals for 15% more each time it travels to a new target.
Monk T15 Mistweaver 4P Bonus: Reduces the cooldown of your Thunder Focus Tea by 10 sec.
Monk T15 Windwalker 2P Bonus: Your Chi generating abilities have a 15% chance to generate an Energy Sphere, which will grant you 10 Energy when you walk through it .
Monk T15 Windwalker 4P Bonus: Increases the damage of your Tigereye Brew by 0.5% per stack consumed.


Paladin





Paladin T15 Holy 2P Bonus: Increases the healing done by your Daybreak ability by 50%.
Paladin T15 Holy 4P Bonus: Increases the healing transferred to your Beacon of Light target by 20%.
Paladin T15 Protection 2P Bonus: Casting Word of Glory or Eternal Flame also grants you 40% additional block chance for 5 sec per Holy Power.
Paladin T15 Protection 4P Bonus: You gain 1 Holy Power for each 20% of your health taken as damage while Divine Protection is active.
Paladin T15 Retribution 2P Bonus: Your Exorcism causes your target to take 6% increased Holy damage from your attacks for 6 sec.
Paladin T15 Retribution 4P Bonus: Your Crusader Strike has a 40% chance to make your next Templar’s Verdict deal all Holy damage.


Priest





Priest T15 Healer 2P Bonus: Your Prayer of Mending heals for 10% more each time it jumps to a new target.
Priest T15 Healer 4P Bonus: Your Penance and Circle of Healing have a 40% chance to summon a Golden Apparition, which moves to a nearby ally and heals for an additional 92500 to 107500.
Priest T15 Shadow 2P Bonus: When your Shadowy Apparitions damage their target, they have a 65% chance to extend the duration of your Shadow Word: Pain and Vampiric Touch, causing each to deal damage one additional time.
Priest T15 Shadow 4P Bonus: Periodic damage from your Vampiric Touch has a 10% chance to trigger your Shadowy Apparition.


Rogue





Rogue T15 2P Bonus: Increases the duration of your finishing moves as if you had used an additional combo point, up to a maximum of 6 combo points.
Rogue T15 4P Bonus: Shadow Blades also reduces the cost of all your abilities by 15%.


Shaman





Shaman T15 Elemental 2P Bonus: Your Lightning Bolt and Chain Lighting spells have an 10% chance to cause a Lightning Strike at the target’s location, dealing 32375 to 37625 Nature damage to all non-crowd controlled targets within 10 yards
Shaman T15 Elemental 4P Bonus: The cooldown of your Ascendence is reduced by 1 sec each time you cast Lava Burst.
Shaman T15 Enhancement 2P Bonus: Unleash Elements also grants you 2 additional charges of Maelstrom Weapon.
Shaman T15 Enhancement 4P Bonus: The cooldown of your Feral Spirits is reduced by 8 sec each time Windfury Weapon is triggered.
Shaman T15 Restoration 2P Bonus: Your Healing Stream Totem now heals an additional target for 25% of its normal amount.
Shaman T15 Restoration 4P Bonus: Your Ancestral Wakening now has a 50% chance to trigger on non-critical heals.


Warlock





Warlock T15 DPS 2P Bonus: While Dark Soul is active, Haunt's duration is increased by 4 sec, Chaos Bolt and Shadowburn consume 20% less Embers, and abilities cost 30% less Demonic Fury.
Warlock T15 DPS 4P Bonus: Your Malefic Grasp and Drain Soul deal 5% more periodic damage, your Incinerate has a 8% chance to generate twice the normal Embers, and your spells generate 10% more Demonic Fury.


Warrior





Warrior T15 DPS 2P Bonus: Your melee auto attacks have a chance to trigger Enrage.
Warrior T15 DPS 4P Bonus: Activating Skull Banner now also increases your critical strike chance by 35% for 10 sec.
Warrior T15 Protection 2P Bonus: Your Shield Slam and Revenge have a 10% chance to activate Victory Rush or Impending Victory as if you had killed your target.
Warrior T15 Protection 4P Bonus: Your abilities generate 50% more Rage when used against targets afflicted by Demoralizing Shout.