Class & Spell Changes Datamined - Season of Discovery Phase 4 PTR

wowhead.com:

With a new Season of Discovery Phase 4 PTR build, we have datamined the newest changes coming to Spells, Item Effects, and Runes for every class!

Season of Discovery Phase 4 PTR Development Notes

Rune Engraving (3)

• 
  Frost:
  Engrave your belt with the Frostfire Bolt rune:
  
  Launches a bolt of frostfire at the enemy, causing \387325 / 100 * (1)] to \451379 / 100 * (1)] Frostfire damage, slowing movement speed by 40% and causing an additional \ Frostfire damage over 9 sec. This spell will be checked against the lower of the target's Frost and Fire resists and counts as both Frost and Fire damage.
  Fire, Arcane:
  Engrave your belt with the Frostfire Bolt rune:
  
  Launches a bolt of frostfire at the enemy, causing \387325 / 100 * 1] to \451379 / 100 * 1] Frostfire damage, slowing movement speed by 40% and causing an additional \ Frostfire damage over 9 sec. This spell will be checked against the lower of the target's Frost and Fire resists and counts as both Frost and Fire damage.
  
• Engrave your boots with the Brain Freeze rune:
  
  Your Frost damage spells with chilling effects have a 20% chance to cause your next Fireball, Spellfrost Bolt, Balefire Bolt, or Frostfire Bolt spell to be instant cast and cost no mana.
  
• Engrave your helm with the Hot Streak rune:
  
  Any time you score 2 non-periodic spell criticals in a row using Fireball, Frostfire Bolt, Balefire Bolt, Fire Blast, Scorch, or Living Bomb, your next Pyroblast spell cast within 10 sec will be instant cast and cost 100% less mana.
  

Spells (1)

• 
  Frost:
  Launches a bolt of frostfire at the enemy, causing \387325 / 100 * (1)] to \451379 / 100 * (1)] Frostfire damage, slowing movement speed by 40% and causing an additional \ Frostfire damage over 9 sec. This spell will be checked against the lower of the target's Frost and Fire resists and counts as both Frost and Fire damage.
  Fire, Arcane:
  Launches a bolt of frostfire at the enemy, causing \387325 / 100 * 1] to