All new Set piece changes are now documented:
Wrath of the Wastes 2 pieces: [Rend deals 400% increased damage.]
Wrath of the Wastes 4 pieces: [Rend lasts 400% longer.]
Wrath of the Wastes 6 pieces: [Whirlwind deals 400% increased damage to enemies affected by your Rend.]
Delsere's Magnum Opus 2 pieces: [Casting Arcane Orb, Energy Twister, Magic Missile or Shock Pulse reduces the cooldown of Slow Time by 1 |4second:seconds;.]
Delsere's Magnum Opus 4 pieces: [Enemies affected by your Slow Time take 1250% weapon damage every second.]
Delsere's Magnum Opus 6 pieces: [Enemies affected by your Slow Time take 500% more damage from your Arcane Orb, Energy Twister, Magic Missile and Shock Pulse abilities.]
Unhallowed Essence 2 pieces: [Your generators also generate 1 Discipline.]
Unhallowed Essence 4 pieces: [Gain 40% damage reduction for 4 seconds if no enemy is within 10 yards of you.]
Unhallowed Essence 6 pieces: [Your generators and Multishot deal 10% increased damage for every point of Discipline you have.]
Roland's Legacy 2 pieces: [Every use of Shield Bash and Sweep Attack reduces the cooldowns of your Laws and Defensive Skills by 1 second.]
Roland's Legacy 4 pieces: [Increase the damage of Shield Bash and Sweep Attack by 500%.]
Raiment of a Thousand Storms 2 pieces: [Your Spirit Generators have 25% increased attack speed and 500% increased damage.]
Raiment of a Thousand Storms 4 pieces: [Increases the weapon damage of Dashing Strike to 5000%.]
Raiment of a Thousand Storms 6 pieces: [Dashing Strike spends 50 Spirit, but refunds a Charge when it does.]
Guardian's Jeopardy 2 pieces: [+250 Vitality] [Regenerates 8000 Life per Second] UP FROM 2000
Zunimassa's Haunt 6 pieces: [Enemies hit by your Mana spenders take 100% more damage from your pets for 4 seconds.]
Inna's Mantra 6 pieces: [Mystic Ally casts Cyclone Strike, Exploding Palm, Lashing Tail Kick, Seven-Sided Strike, and Wave of Light when you do.]
Inna's Mantra 2 pieces: [Increase the passive effect of your Mystic Ally and the base passive effect of your Mantra by 100%.]
Tal Rasha's Elements 2 pieces: [Damaging enemies with Arcane, Cold, Fire or Lightning will cause a Meteor of the same damage type to fall from the sky. There is an 8 second cooldown for each damage type.]
Tal Rasha's Elements 4 pieces: [Attacks increase your resistance to that damage type by 100% for 6 seconds.]
Tal Rasha's Elements 6 pieces: [Attacks increase your damage by 75% for 3 seconds. Arcane, Cold, Fire, and Lightning attacks each add one stack. Adding a stack refreshes the duration.]
Immortal King's Call 2 pieces: [Call of the Ancients last until they die.]
Immortal King's Call 4 pieces: [Call of the Ancients' melee attacks also deal 600% weapon damage in a 15 yard radius.]
Immortal King's Call 6 pieces: [Increase the duration of your Wrath of the Berserker by [0.5|1|] |4second:seconds; every time an Ancient deals damage.]
Natalya's Vengeance 4 pieces: [The cooldown of Rain of Vengeance is reduced by 2 seconds every time you cast a primary skill and by 3 seconds every time you cast a Hatred spender.]
Natalya's Vengeance 6 pieces: [Rain of Vengeance deals 800% increased damage.]
Wrath of the Wastes 2 pieces: [Rend deals 400% increased damage.]
Wrath of the Wastes 4 pieces: [Rend lasts 400% longer.]
Wrath of the Wastes 6 pieces: [Whirlwind deals 400% increased damage to enemies affected by your Rend.]
Delsere's Magnum Opus 2 pieces: [Casting Arcane Orb, Energy Twister, Magic Missile or Shock Pulse reduces the cooldown of Slow Time by 1 |4second:seconds;.]
Delsere's Magnum Opus 4 pieces: [Enemies affected by your Slow Time take 1250% weapon damage every second.]
Delsere's Magnum Opus 6 pieces: [Enemies affected by your Slow Time take 500% more damage from your Arcane Orb, Energy Twister, Magic Missile and Shock Pulse abilities.]
Unhallowed Essence 2 pieces: [Your generators also generate 1 Discipline.]
Unhallowed Essence 4 pieces: [Gain 40% damage reduction for 4 seconds if no enemy is within 10 yards of you.]
Unhallowed Essence 6 pieces: [Your generators and Multishot deal 10% increased damage for every point of Discipline you have.]
Roland's Legacy 2 pieces: [Every use of Shield Bash and Sweep Attack reduces the cooldowns of your Laws and Defensive Skills by 1 second.]
Roland's Legacy 4 pieces: [Increase the damage of Shield Bash and Sweep Attack by 500%.]
Raiment of a Thousand Storms 2 pieces: [Your Spirit Generators have 25% increased attack speed and 500% increased damage.]
Raiment of a Thousand Storms 4 pieces: [Increases the weapon damage of Dashing Strike to 5000%.]
Raiment of a Thousand Storms 6 pieces: [Dashing Strike spends 50 Spirit, but refunds a Charge when it does.]
Guardian's Jeopardy 2 pieces: [+250 Vitality] [Regenerates 8000 Life per Second] UP FROM 2000
Zunimassa's Haunt 6 pieces: [Enemies hit by your Mana spenders take 100% more damage from your pets for 4 seconds.]
Inna's Mantra 6 pieces: [Mystic Ally casts Cyclone Strike, Exploding Palm, Lashing Tail Kick, Seven-Sided Strike, and Wave of Light when you do.]
Inna's Mantra 2 pieces: [Increase the passive effect of your Mystic Ally and the base passive effect of your Mantra by 100%.]
Tal Rasha's Elements 2 pieces: [Damaging enemies with Arcane, Cold, Fire or Lightning will cause a Meteor of the same damage type to fall from the sky. There is an 8 second cooldown for each damage type.]
Tal Rasha's Elements 4 pieces: [Attacks increase your resistance to that damage type by 100% for 6 seconds.]
Tal Rasha's Elements 6 pieces: [Attacks increase your damage by 75% for 3 seconds. Arcane, Cold, Fire, and Lightning attacks each add one stack. Adding a stack refreshes the duration.]
Immortal King's Call 2 pieces: [Call of the Ancients last until they die.]
Immortal King's Call 4 pieces: [Call of the Ancients' melee attacks also deal 600% weapon damage in a 15 yard radius.]
Immortal King's Call 6 pieces: [Increase the duration of your Wrath of the Berserker by [0.5|1|] |4second:seconds; every time an Ancient deals damage.]
Natalya's Vengeance 4 pieces: [The cooldown of Rain of Vengeance is reduced by 2 seconds every time you cast a primary skill and by 3 seconds every time you cast a Hatred spender.]
Natalya's Vengeance 6 pieces: [Rain of Vengeance deals 800% increased damage.]