http://www.wowhead.com/news=258937/7-1-5-ptr-hotfixes-for-january-5th-tier-19-set-bonuses

Set Bonuses
Item - Death Knight T19 Frost 4P Bonus:  Howling Blast now generates 10->8 Runic Power while Rime is active.
Item - Druid T19 Balance 4P Bonus:  Starsurge deals 20%->15% increased damage to targets affected by both your  Sunfire and  Moonfire.
Item - Druid T19 Feral 4P Bonus:  Shred and  Swipe deal 10%->15% increased damage for each Bleed effect you have on the target.
Item - Hunter T19 Beast Mastery 2P Bonus:  Dire Beast reduces the cooldown of  Bestial Wrath by an additional 3->sec.
Item - Hunter T19 Survival 2P Bonus:  Flanking Strike now has 2->3 times the normal chance to trigger  Hunting Companion.
Item - Hunter T19 Beast Mastery 4P Bonus: When you use  Bestial Wrath, all of your currently summoned  Dire Beasts gain 100%->50% increased damage for 815 sec.
Item - Hunter T19 Marksmanship 4P Bonus:  Trueshot also reduces the cost of all your Focus spenders by 50%->15%.
Item - Mage T19 Fire 2P Bonus:  Enhanced Pyrotechnics provides an additional 10%->20% critical strike chance from each application.
Item - Monk T19 Windwalker 2P Bonus: Reduces the cooldown on  Rising Sun Kick by 2->3 sec.
Item - Monk T19 Windwalker 4P Bonus: Using 3 sequentially different abilities grants 1500->2000 Mastery for 10 sec.
Item - Paladin T19 Retribution 4P Bonus: Your Holy Power generating abilities have a 15%->20% chance to generate 1 additional Holy Power.
Item - Rogue T19 Outlaw 2P Bonus:  Saber Slash has an additional 40%->30% chance to trigger  Mastery: Main Gauche.
Item - Rogue T19 Subtlety 4P Bonus:  Shadowstrike has a 100%->30% chance to generate an additional combo point when used on targets affected by your  Nightblade.
Item - Shaman T19 Elemental 4P Bonus:  Elemental Focus increases damage and healing by an additional 15%->10%.
Item - Warlock T19 Destruction 2P Bonus: Casting Chaos Bolt reduces the cast time of your next  Chaos Bolt by 30%->40% for 4 sec.
Item - Warrior T19 Arms 2P Bonus: Increases the duration of  Battle Cry by 3->2sec.