Primary Issue:
The game was not tested for AI difficulty using any type of standards for Easy, Normal, and Hard.

Goal:
Align all campaigns on difficulty
Make sure Hard is challenging to a seasoned veteran

Editing AI files:

Note for Normal:
Handicap removed from all missions

Definitions:

Easy (Story Mode)

Players should require minimal RTS experience
One hand rule
Players should be allowed to make many mistakes and recover
Experiencing the cutscenes, scripted gameplay moments, and plot are the priority
Attack move is expected

Normal

Players should be allowed to make mistakes with minimal punishment
Players should be using their keyboard to build and use unit abilities
Attack move is expected

Hard

Players should be punished for mistakes
Bosses and similar pivotal gameplay moments should be memorable due to how hard they are, while remaining interesting
Players will be expected to use most of the tools at their disposal to complete a mission
Targeting individual units by priority is expected
"Gold Stress" should come into play, meaning the player should feel as though they need to expand at some point rather than relying on a single mine without concern.

General:

Anecdotally I've heard that the efforts to reduce "wasted" startup time building bases has been appreciated. We did this numerous times by providing more workers and making sure they are harvesting coming out of cutscenes. We should look into how we can apply this further.

RoC

Prologue

PR01

Normal

2x Gnoll and 1x Gnoll Poacher replaced with 2x Gnoll Brute and 1x Gnoll Assassian at camp

Hard

+1 Gnoll Overseer at camp

All difficulties

Narrator VO first Gnoll will not play or truncate if you attack before they are finished speaking
Narrator VO for a-moving into the Gnoll camp will not play or truncate if you are already moving in
These resolve an issue where the Narrator would be speaking over you doing the thing he's preparing you for
Gnoll camp exit is blocked until you kill all the Gnolls
Players could run past, skipping the experience and more importantly level 2 and the lesson on Chain Lightning
There is a text Hint if you near the barrier while Gnolls are alive
This is the watershed moment of the map so the difficulty is focused here

PR02

Hard

Enemy AI has level 1 weapon, armor, and Improved Masonry upgrades
+2 Footmen at far side bridge
+2 Footmen, +1 Knight at gate 1
+2 Footmen at cage 2
+3 Riflemen at firing range
+1 Knight at cage 3
+2 Footmen at gate 2
+1 Captain, +1 Knight, +2 Riflemen at base

PR03

Hard

Did not exist
Enemy AI has level 1 weapon, armor, and Improved Masonry upgrades

Bugs

Debug triggers were on

PR04

Hard

Enemy AI has level 1 weapon, and armor upgrades
Player has level 1 weapon and armor upgrades instead of level 2

PR05

Hard

Did not exist
Buildings seen as damaged in the intro are not repaired

Human

These will be used as controls for the campaigns

HU01

Hard

+1 Gnoll at Timmy
+2 bandits at bandit camp for Ledger
+3 Grunts when entering town
+1 Grunt at Slave Master
AI starts with level 1 armor and weapon upgrades
Orc forces will now rush to defend their leader if you move directly to him
Benedict no longer disabled

Bugs

VO and quest triggers no longer stack and overlap if you run past triggered events
You no longer see units pop out of existence in the mid scene

HU02

Hard

-2 Scout Towers at player base
+2 Grunts, +3 Axethrower at Blademaster
+2 Grunts, +1 Watch Tower, +1 Barracks at Blackrock Clan base
+1 Grunt, +1 Raider, +1 Watch Tower at center
+2 Black Drake road to Searinox
AI starts with level 1 armor and weapon upgrades

HU03

Hard

+2 Bandit Rogues at village ambush
+2 Murloc Huntsman at Murloc Island
+6 Skeleton Archers at ambush
+4 Skeleton Warriors at pre-KT fountain
Skeleton Warriors replaced with Giant Skeleton Warriors at KT
Ghoul rush from wheat increased from 4 to 8 at KT
Ghoul rush from rear +4 each side of buildings at KT
Final Barn rush doubled
AI starts with level 1 armor and weapon upgrades

All difficulties

+1 Puddle Lord Envoy (Murloc Flesheater) at Murloc island - Reference to UDx03

HU04

Normal

+1 Abomination outside KT

Hard

Starting mine reduced to 8000
Expansion mine reduced to 6000
Replace Potion of Mana Enforcer with Bandit Lord
+6 Ghouls, +2 Giant Skeleton Warriors spawn and attack after Granary cutscene
+2 Giant Skeleton Warriors, +1 Abomination at KT throne
Abominations at KT Throne now warp in surrounding the player
+3 Abominations outside KT area
Wave 2 +2 Abominations
Wave 3 +2 Abominations
Wave 4 +4 Abominations
Wave 5 +3 Abominations
Wave 6 +4 Abominations
Wave 7 +2 Abominations
AI starts with level 1 armor and weapon upgrades, Disease Cloud

All difficulties

+1 Spirit Tower outside KT
Swap Slaughterhouse at KT with Altar of Darkness
+2 Slaughterhouses at green base
Fight with KT is now more substantial. 3/5/8 Aboms will warp in to defend him.
KT further adjusted to be a hero unit and will use Death Pact to heal himself.
Wave 1 M5,M5,M1 -> M5,M3,M1
Wave 2 M6,M6,M3 -> M5,M4,M2
Wave 3 M5,M5,M3 -> M5,M3,M2
Wave 4 M5,M5,M4 -> M5,M3,M2
Wave 5 M6,M6,M3 -> M6,M4,M2
Wave 6 M5,M5,M4 -> M5,M3,M2
Wave 7 M6,M6,M3 -> M6,M4,M2
A wave of zombies will emerge from the trees if you get past the Abominations

HU05

Hard

+30 intro zombies
Green:
Wave 2 +2 Ghouls, +1 Necro, -1 Meat Wagon
Wave 3 +Hero
Wave 4 +4 Ghouls, +2 Necromancers
Wave 5 +4 Necromancers, +2 Abominations
Wave 6 +Hero, -2 Meat Wagons
Wave 7
Wave 8 +4 Ghouls, +2 Abominations, -3 Meat Wagons, +Hero
Purple
Wave 5 -2 Meat Wagon
Wave 6 -1 Meat Wagon
Wave 8 -2 Meat Wagon
Wave 10 -1 Meat Wagon
All attack wave intervals increased by 2 minutes through 25 minutes, after all waves increased by 1 minute
Orange
-1 Meat Wagon, -1 Abomination, -1 Necromancer

All difficulties

Lich heroes were not configured per difficulty level, they are now: Green/Purple, 2/3, 4/5, 6/7
Ordering forces to move to the first village no longer paths through Green's base
Waves with Liches reduced in size

HU06

Hard

Starting units no longer reduced
Damage of Meathook Disease Cloud increased from 16/sec to 28/sec
Enemy AI starts with level 1 Armor and weapon upgrades, Disease Cloud

Purple:

Wave 1 +4 Ghouls

All difficulties

Purple shares upgrades with Green
Easy/Normal damage of Meathook Disease Cloud increased from 12/sec ro 18/sec, all difficulties auto attack damage increased from 52 to 72
Salramm the Fleshcrafter: Base damage increase from 7 to 45, auto attack is AoE, cooldown decreased from 1.8 to 1.4

HU07

Hard

+2 Frost Wolfs at first choke
Replace three Ice Trolls with Ice Troll Berserkers
Enemy AI starts with level 1 Armor and weapon upgrades, Disease Cloud
Remove starting Priest
Expansion mine reduced from 12500 to 9000
Opening mine reduced from 9000 to 7000
Green:

Wave 1 +2 Ghouls
Wave 2 +3 Gargoyles, + 0/2/5 Ghouls, 1 minute faster
Wave 3 +1 Abomination, +2 Necromancers
Wave 4 +3 Gargoyles, + 0/2/6 Ghouls
Wave 5 +1 Abomination
Wave 6 +0/4/8 Ghouls
Wave 7 +3 Abominations
Wave 9 +0/4/8 Ghouls
Wave 10 +2 Abominations
+1 Slaughterhouse
+3 Spirit Towers in base
+2 Spirit Towers out of base with small guard force
+1 Crypt

All difficulties

Main mine gold reduced from 24680 to 9000
Expansion mine gold reduced from 20000 to 12500
1 Frost Wolf replaced with Giant Frost Wolf at first choke
Small attack wave after mid cutscene
Start with a Lumber Mill
Green Lich was not scaled. He is now 5/7/9
Green Lich was not limited from leveling

HU08

Normal

+3 Giant Skeleton Warriors at Graveyards

Hard

Enemy AI starts with level 1 Armor and weapon upgrades, Disease Cloud
+1 Abomination at first encounter
+2 Abominations at second encounter
+2 Abominations at third encounter
+2 Nerubian Seers at Nerubian village
+7 Giant Skeleton Warriors at Graveyard

All difficulties

Gold mine scales: 12500/9000/6000

HU09

Hard

Enemy AI starts with level 1 Armor and weapon upgrades, Disease Cloud
Escort for guantlet reduced to 1 Knight and 1 Rifleman
Purple starts with 1 more Graveyard

All difficulties

Green

Pre-sword

Wave 1 Timing M8,M8,M7 -> M8,M6,M3
Wave 2 Timing **M10,M10,M7 -> M10,M7,M4
Wave 3 Timing M8,M8,M7 -> M8,M6,M4
Wave 4 Timing M10,M10,M7 -> M10,M7,M4
Wave 5 Timing M8,M8,M7 -> M8,M6,M4
Wave 6 Timing M10,M10,M7 -> M10,M7,M4
Wave 9+ Timing M8,M8,M7 -> M8,M6,M4
M10,M10,M7 -> M10,M7,M4

After the Sword

Wave 9+ Timing after sword

Purple

M10,M10,M8 -> M10,M8,M6
M10,M10,M9 -> M10,M8,M7
M10,M10,M8 -> M10,M8,M6
M10,M10,M9 -> M10,M8,M7
No more than 2 Meat Wagons per wave
The AI was stacking wait times for wave 1 after the sword. There is now an attack wave immediately after the cutscene from all three directions of small forces
Mal'Ganis was Level 9 on all difficulties, he's now 8/9/10
Mal'Ganis is now warped away when he's close to death rather than being killable outright on attack waves
Main gold mine reduced from 30,000 to 30000/10000/7000
Golem mine reduced from 15000 to 8000
Green expo mine reduced from 25000 to 12500
Purple mine reduced from 25000 to 12500
Three extra Scout Towers provided. On Easy they are Cannon Towers.
Green no longer has infinite gold. Instead it normally harvests and is supplemented by the smaller Western UD base.

Bugs

Mal'Ganis was missing two of his abilities
AI's would only rebuild some buildings at some difficulty levels, and there were duplicate entries.
Teal's AI was non-functional due to missing starting lumber

Undead

UD01

Hard

Enemy AI starts with level 1 Armor and weapon upgrades
-1 Ghoul, -1 Skeleton Warrior at the Graveyard

UD02

Hard

Enemy AI starts with level 1 Armor and weapon upgrades
+3 Mud Golems at golem field
Gold mine reduced from 50,000 to 20,000

UD03

Normal

There is now a timer that destroys the treelines restricting the AI at 6m
Yellow and teal AI's will send small attack forces

Hard

Enemy AI starts with level 1 Armor and weapon upgrades
There is now a timer that destroys the treelines restricting the AI at 3m
Yellow and teal AI's will send small attack forces
Starting gold mine reduced from 13000 to 7000
Natural expansion gold mine reduced from 15000 to 6000
Two small outposts added on the way to Farstriders base

All difficulties

Expansion mines default to 12500

Bugs

Normal handicap trigger was disabled
Escaping rapidly could break the opening camera

UD04

Hard

Enemy AI starts with level 1 Armor and weapon upgrades
Main mine gold reduced from 14500 to 11000
Sylvanas is level 8 and has Starfall
+2 Earth Fury towers at each Magic Vault

All difficulties

Expansion mines set to 12500

UD05

Hard

Enemy AI starts with level 1 Armor and weapon upgrades
Sylvanas is level 8 and has Starfall
Main gold mine reduced from 14000 to 8000
Expansion gold mine reduced from 20000 to 12500
Zeppelin drops include a level 6 Rock Golem

All difficulties

+4 Moss Covered Granite Golems at Sunwell
Sunstrider Isle revised, removed Waygates, +1 Wagon with Potion of Mana
Fountain of Power replaced with Fountain of Health
City revised to be more city-y
Side quest clarification
Prevent all runners from reaching Silvermoon before breaching the city
In connection with lore you'll now see the Dead Scar after the Ice Bridge cinematic

Bugs

Rapidly escaping the intro could break the camera
Rushing to the city could result in both failing and completing the optional quest

UD06

Hard

Enemy AI starts with level 1 Armor and weapon upgrades, and Spiked Barricades
Enemy heroes start with +2 levels and all have their ultimates
Teal attack force attacks immediately after the intro cutscene
Main gold mine reduced from 18000 to 8000
Red AI is enabled with all the others, the first wave you face will be two Red Dragons

Bug fixes

Enemy heroes were not experience locked
Enemy AI's would not rebuild and were not configured for different difficulties

UD07

Hard

Pain field damage increased from 15/18/21 to 20/25/30
Main gold mine reduced from 12500 to 8000
Enemy AI starts with level 1 Armor and weapon upgrades, Storm Hammers, and Defend

All difficulties

1 Crypt replaced with 1 Slaughterhouse

UD08

Hard

Enemy AI starts with level 1 Armor and weapon upgrades, Storm Hammers, Flying Machine Bombs, and Defend
Main gold mine reduced from 14000 to 8000
Expansion gold mine reduced from 12500 to 10000
Starting resources reduced by 50%

All difficulties

Start with Black Citadel
Expansion gold mine reduced from 25000 to 12500

Bug fixes

Archmagi could be level 1 due to order of operations in triggers

Orc

Orc01

Hard

Tauren have level 1 attack and armor upgrades instead of level 3's. Normal and Story Mode unchanged.
-1 Headhunter at first ship
-1 Grunt at second ship

All difficulties

Level 1 attack and armor upgrades, Brute Strength, and Troll Regeneration no longer researched for the player except on Story Mode
All rescuable Tauren have 4x starting HP % to make them attempting to rescue them less frustrating

Orc02

Hard

-2 starting Headhunters
-1 Grunt reinforcement
-1 Raider reinforcement
-1 Demolisher reinforcement

All difficulties

Upgrades match Orc01

Orc03

Hard

AI build one extra of their primary unit composition production building
Purple initial delay reduced from 2 to 1 minute
Main mine reduced from 21,000 to 10,000
Enemy AI start with level 1 armor and weapon upgrades

All difficulties

AI attack frequency reduced by 1 minute on Normal and Hard
AI will now rebuild on Normal and Hard
Grommash will now begin his attack timer after the mid custscene rather than waiting until the Great Hall is completed
Expansion mines reduced from 22100-24000 to 12500
Main mine reduced from 21,000 to 14,000 on Easy and Normal
Thralls VO indicated there should have been a way to complete the main quest without attacking the Humans. There is now a hidden path with a special surprise.

Orc04

Hard

Reduced attack intervals for all AI by 1 minute
Other than Ai attack timing there was no Hard mode at all
Enemy AI start with level 1 armor and weapon upgrades
West expansion gold mine reduced from 40000 to 20000

Orc05

Hard

Main mine reduced from 20000 to 9000
Expansion mine reduced from 12500 to 10000
Enemy AI start with level 1 armor and weapon upgrades

All difficulties

Main mine reduced from 30000 to 20000
Expansion mine reduced from 20000 to 12500

Orc06

Hard

Enemy AI start with level 1 armor and weapon upgrades
Main mine reduced from 14000 to 9000
Expansion mine reduced from 18000 to 12500

All difficulties

Main mine reduced from 22500 to 14000
Expansion mine reduced from 25000 to 18000
AI was not configured to rebuild
Map route is not revealed where the Zeppelin was in the intro cutscene

Bugs

Main gold mine and harvested amount varied based on how long you watched the intro

Orc07

Hard

Human Enemy AI start with level 1 weapon and armor upgrades

All difficulties

Remove revealed area from intro cinematic

Orc08

Easy

+2 Guard Towers at Jaina
+3 Watch Towers at player base
Jaina starts with level 1 armor, weapon, and magic upgrades

Normal

+2 Guard Towers at Jaina
+3 Watch Towers at player base

Hard

Main mine reduced from 20000 to 14,000
Expansion mines reduced from to 9000

All difficulties

Main mine reduced from 30000 to 20000
Expansion mines reduced from to 12500 (including Jaina's mine)
Legacy Infernal wave restored
If a player did not complete the optional quest in Orc06 they will get the new unit message for Wyvern

Bugs

Dark Green's AI was not given starting resources so it could not build anything requiring lumber
There was a mix of Fel and standard Burrows for both Orc AI, and they were missing Fel Burrows from their build tree resulting in being unable to rebuild food production
Jaina AI was not rebuilding most of her base, and would never utilize Gryphons
Skipping the intro rapidly could break the camera

Night Elf

NE01

Hard

There was no Hard mode
Enemy AI start with level 1 weapon and armor upgrades
Enemy AI attack timer starts after the intro instead of upon completing the base building quest
Main gold mine reduced from 12500 to 9000
Expansion gold mines reduced from 12500 to 8000
Enemy AI was not configured to rebuild

NE02

Hard

Enemy AI start with level 1 weapon and armor upgrades
-2 Archers at 1st reinforcement
-1 Huntress at 2nd reinforcement
-1 Huntresses at 3rd reinforcement
-1 Glaive Throwers at final reinforcement
-2 Archers at final reinforcement
Secret path must be entered from second entrance
1 Abomination and 2 Crypt Fends greet you on the secret path

All difficulties

Replace Human bridge with Elven bridge
AI was not reacting or rebuilding
AI will now protect itself when the Ziggurat near secret entrance 2 is attacked
Triggers for the timed moonlight/sunlight weren't working correctly, they are meant to signal day/night shift

Bugs

One of Green's buildings was owned by an enemy and would be killed immediately at game start

NE03

Hard

Enemy AI start with level 1 weapon and armor upgrades
Main gold mine reduced from 14500 to 9000
Expansion gold mines reduced from 12500 to 8000
Wave 1 attack time reduced from 4 to 2 minutes
Following waves reduced from 4 to 3 minutes

All difficulties

Replace 1 Murloc Nightcrawler with Puddle Lord Envoy (Murloc Flesheater) at Murloc island - Reference to UDx03

Bugs

Trigger to detect Guardian deaths did not filter out corpses so a player may need to wait 60 seconds after killing the last Guardian before the outro starts

NE04

Normal

No longer remove 2 Cannon Towers

Hard

Enemy AI start with level 1 weapon, armor, and magic upgrades
Corrupted NE
Second wave is 1 minute faster
Plague Treants added to attack waves

All difficulties

Human and Corrupted NE AI's would not rebuild, and Corrupted NE could not repair

NE05

Hard

No longer have level 1 armor upgrades
-3 Archers at prison rescue

All difficulties

Circles of Power at gate turn blue once activated
Gates "explode" in correct directions
Outro scene part 2 no longer shows the gate opening and units being placed. There's also 1 DoC removed to better frame MalFurion.

NE06

Hard

Enemy AI start with level 1 weapon and armor upgrades
Plague Treants included in attack waves
All brown attack waves 2 minutes faster
Reduce Southern expansion mine from 10000 to 6000
Reduce Northern expansion mine from 12500 to 9000
Reduce main mine from 14000 to 9000

All difficulties

AI now rebuilds besides Tree of Eternities
Reduce Southern expansion mine from 17500 to 10000
Reduce Northern expansion mine from 23500 to 12500
Reduce main mine from 18500 to 14000

Bugs

Brown AI had a double wave in the beginning
Illidan no longer has cinematic anims after intro

NE07

Hard

Enemy AI start with level 1 weapon, armor, and magic upgrades
Main and two expansion mine gold amounts reduced by 50%

All difficulties

Friendly AI would not rebuild
Chimaeras available

TFT

Remove handicaps from Normal and Hard
Give enemy AI +1 upgrades on Hard
Reduce available gold on Hard

Legacy Note:

HUX02 - Part 1 advancing forces had +3 upgrades
HUX03 - Enemy units had +3 attack upgrades
NEX03 - Siren training was at +2
NEX06 - End UD forces had +2 upgrades
NEX08 - Enemy units had +3 upgrades
UDX01 - Enemy units had +3 upgrades
UDX02 - Enemy units had +2 upgrades
UDX03 - Was missing Hard mode
UDX04 - Main Human base has +3 building armor