Gameplay Improvements
Campaign
It is now possible to levy units from satrapies and client states. This works in a similar manner to mercenaries, but these units have normal recruitment and upkeep costs, and come from the locally available unit roster.
Infantry and cavalry units now have different campaign movement extents. Infantry units are slower than before, while cavalry units are faster than before. Armies always move at the speed of the slowest unit. Now cavalry-only armies actually move faster.
Cinematic borders can now be displayed in campaign and battle by pressing [ALT] + [K] keys (by default).
New industrial building chain: Quarry and mine buildings are now available for construction in minor settlements for all factions.
Fixed an issue that prevented the AI from blockading the Brundisium port.
Improved cultural conversion mechanics.
Exempting a province from tax now sets its food consumption to zero (this wasn't previously registering).
In Multiplayer Campaign mode, when a player-owned settlement is attacked by the AI, the player will no longer have the option to sally forth, when the 'fight manual battles' option is disabled.
Improved disembarkation areas in some coastal battle maps.
Special abilities in battle have undergone rebalancing.
Changed victory conditions in grand campaign for all playable factions. The number of regions the player needs to control in order to win the game has been reduced.
Removed a number of misleading treachery types from Diplomacy, so now a faction that breaks a treaty and then signs it again within 10 turns won't get treachery penalties.
Campaign AI is now less likely to declare war on too many factions.
Battle
Added new Barbarian major port battle map.
Enemy reinforcement banners no longer begin battle as visible, thereby initially hiding the units' positions in battles.
Added visualisations to denote the range of targeted abilities in battles, so the player will know which units will be affected.
Fixed a bug which caused the frame rate drop when it rained during battles.
Usability Improvements
Campaign
After researching a technology on the campaign map, the zoom-to-location button on the Research Complete message will now zoom to the correct location.
Faction list in Diplomacy now sorts alphabetically by default.
The Toggle UI shortcut ([K] key by default) now works with Campaign modes.
Treachery warnings now show reliably when you are declaring war and have current treaties with that faction. The warning also shows when the player breaks a treaty and tries to declare war, while the treaty is still in the process of being broken.
Fixed the top and bottom of the Campaign tactical map to prevent it from being clipped at high resolutions.
Added borders to the campaign tactical map so regions at the edges can be seen more centrally and are not blocked by the diplomacy user interface.
wiki.totalwar.com/w/Total_War_ROME_II:_Patch_8
Fixed a conflict which meant automatically constructed siege equipment prevented the player from building anything else.
General's skills and army traditions which lower upkeep costs will now update the recruitment panels correctly.
Agent ability Intercept Orders success event-messages will now display which specific armies/settlements are revealed.
Improved trees on the Campaign map.
Battle
Post-battle loading screens for Custom/Multiplayer battles are now interactive, so the player can see kills/losses of armies in battle.
When reinforcing an ally in a campaign battle using multiple armies, the unit cards in battle will now be adapted correctly to the number of unit cards and fit the screen correctly.
It is now clearer in the battle UI when auto-trigger is enabled on ability buttons.
Improved lighting and vegetation in Atlantic climate battles.