Let's have the grand old overview of changes:
MODDING:
Faction mods
Unit replacement mods
Hero replacement mods
Projectile mods
Modding guide
GENERAL:
Healing skill rework
Infirmary mechanic rework
Hospital mechanic added
Units gained through mastery now show up as small overworld messsages
Rest of town screens implemented
Heroes can gain support from nearby guardposts when attacked
11 new unit abilities (taxpayer, thorns, fire shield, tower, chaos, displacement, buffer, empower, inert, insensate, shadowmancy)
End of Game graph has been updated to be clearer
Being defeated gives option to continue watching
Winning a map gives option to return to main menu
Rebalanced difficulty of neutral mobs across the starting area
Bodyguards skill rework
20 new achievements
Fixes to Town fort reinforcements, and being able to see these units on hover-over
AI improvements (still more to come)
Hero fleeing mechanics changes
MANA:
Spells are 1 mana cheaper
Casters start with +1 knowledge
Levelling up knowledge gives +10 mana
Higher cost spells are now even more powerful
WILD & PYRE CHANGES:
Symbiotic Grove is now required for Overgrowth
Symbiotic Grove is now on row 1
Everburning Flame is now required for Mine Portals
LAMENT:
New Insensate ability for Trogserkers and Minotaur+Goldhorns
New tier 6 units: Shadowmancer and Aspect of Shadow
Dragontemple reworked
Building order has been changed
OBELISKS:
New vision-based treasure hunting system
Added Obeluses, obelisk fragments that spawn when interacting with an obelisk
BATTLE CONTROLS:
Units can be grouped together in single groups, and split apart (shift to merge, right click to split)
Game automatically groups similar units and places them reliably across the battlefield
You can now drag units up from the reserve panel in the bottom to place them on the battlefield
During combat, you can click a unit portrait at the top to give movement orders to only that type of unit