Dragonflight Season 4 Tier Set Changes in the War Within Pre-Patch

wowhead.com:

Blizzard has announced that some Dragonflight Season 4 Tier sets are being changed in the War Within Pre-Patch tomorrow.

• DEATH KNIGHT
  Unholy
  
  Dragonflight Season 4 class set bonuses have been updated to the Dragonflight Season 1 class set bonuses:
  
  2 Set Bonus – Bursting a Festering Wound grants your ghoul Vile Infusion, increasing their damage by 25% and Haste by 10% for 5 seconds.
• 4 Set Bonus – Your primary ghoul's attacks have a 8% chance to increase your damage and Haste by 8% for 8 seconds. This chance is increased to 15% during Vile Infusion.
• Developer's note: In The War Within pre-patch we had several season 4 class sets that were made into spec talents. In order to prevent any oddities we are updating those select few class sets with earlier tier sets from Dragonflight to prevent any overlap or potential bugs.

EVOKER

• Preservation
  Dragonflight Season 4 class set bonuses have been updated to the Dragonflight Season 2 class set bonuses:
  
  2 Set Bonus – Spiritbloom applies a heal over time effect for 40% of healing done over 8 seconds. Dream Breath's healing is increased by 15%.
• 4 Set Bonus – After casting 5 empower spells, gain Essence Burst immediately and another 3 seconds later.
• Developer's note: In The War Within pre-patch we had several season 4 class sets that were made into spec talents. In order to prevent any oddities we are updating those select few class sets with earlier tier sets from Dragonflight to prevent any overlap or potential bugs.

MAGE

• Arcane
  Dragonflight Season 4 class set bonuses have been updated to the Dragonflight Season 1 class set bonuses:
  
  2 Set Bonus – For each Arcane Charge, Arcane Blast critical strike chance is increased by 3% and Arcane Explosion critical strike chance is increased by 3%.
• 4 Set Bonus – When Arcane Blast or Arcane Explosion critically strikes at least one target, the critical strike chance of your next Arcane Barrage is increased by 10%, stacking up to 4 times.
• Developer's note: In The War Within