Background
CoE has a hidden score, called "World Progression" in the difficulty setup menu, that dictates many things related to enemy strength.  There is both a time component (7 points per in-game day) and a scaling factor (10 points per research and 100 points per tower level).  Completing certain researches, like Teleport, Recall, the Tower movement spells (and its upgrades) give 50 progression points instead of 10.  And the most powerful spell (usually Titan summoning or a global enchantment) per school gives 100 points instead of 10.

These Progression points are modified by the difficulty level (0.5x on the easiest difficulty, 1.2x on the highest difficulty).  In the main campaign, these points then cause enemies to increase in strength when certain thresholds are crossed (0, 200, 500, 800, 1200, 1500, 1800, 2100, 2400, 2700, 3000, 3300, 3700, 4100, 4500 points).

This mod starts to change things around Progression level 9 (level 8 in the mod files, since those are zero-indexed).  On the highest difficulty, if you reach mastery level 50+ and research 50 spells (including the tower movement, teleportation and one school's ultimate spell), you'll reach this progression around week 16 of the game.  About every 5 weeks afterwards (faster if you keep researching) will increase the Progression by another level, up until level 15.

This mod also includes 6 additional world progression difficulty levels, each bringing maximum world progression 3-5 weeks sooner.  Of course, this will also make the game much harder, so increment with caution!  I recommend incrementing this difficulty once for every mod that increases the player's power (such as Orkze's More Unit Levels) and 2 additional increments if you play with 2 crafting classes.

Note: Progression level changes don't apply to games retroactively.  To see the majority of the changes in this mod, you'll need to start a new game.

Feel free to discuss here or on the Steam forums.

Note: Demon Scourge and Weaver's Realms DLCs are both required.  This is primarily because Uram and Ianna's changes use assets and features from those DLCs.  And also because it is already very difficult to test a single version of the mod, let alone versions for each DLC combination.

Antagonist Changes
Antagonists are made stronger through some thematically appropriate buffs, some of which may be stronger than others.

All Antagonists

• Progression 7 - All units get Nor's Grip.  All Fantastic units get Infused Memory.
• Progression 15 - All units get +20% HP and damage.
  

Gor

• Progression 7 - Fantastic units gain the Beast tag.
• Progression 9 - All units get Nature's Vengeance.
• Progression 10 - All beasts get Undying.  Spellcasters gain a Spider bodyguard.  Goblins gain Lycanthropy, causing them to revive as Minor Wendigos (weaker version of the Wendigo Demon) upon death.
• Progression 11 - Gets an extra Stackslot, bringing his total up to 9.  This slot is a Titan, such as a Treant, Flesh Colossus, or Arachnoid Abomination.
• Progression 12 - All units get Frenzy, Regeneration, and +20 HP.
• Progression 13 - All units get Life Stealing (50% vs all).
• Progression 14 - All units get Agile, Effortless Defense, and Total Awareness.
  

Hokan

• Progression 9 - Haunted Armor grants 50% elemental resist to allies around it.  Player undead are stunned every turn.
• Progression 10 - 3x Undead Ritualists appear as enemy reinforcements in all battles.  These units cast a stacking map-wide White damage debuff.  Note: Apparently a single stacked Aura-granting status effect cannot stack its effects on enemies.  So I've created 10 identical Auras that trigger the next Aura-granting status effect on death.  So each Undead Ritualist can provide up to 10 instances of the white-debuff aura.  This unfortunately clogs up the status effect display on player units.  Damage displays can go negative, but there is a minimum damage of 1.  I wanted these debuffs tied to the life of the Ritualists, which is why they are implemented as Auras.
• Progression 11 - Gets an extra Stackslot, bringing his total up to 10.  This slot is a Titan, such as a Flesh Colossus.
• Progression 12 - All units gain Death Incarnate.
• Progression 13 - All Undead units gain Undead Officer.
• Progression 14 - All units gain Eery Overlord.
  

Ianna
To Emulate the Dreamweaver's Mindwipe spell, Ianna's units have a different level progression than ordinary units, more similar to Heroes than units.  They get major upgrades every 3 levels and at level 14, for a total of 6 major upgrades.  And Ianna's progression upgrades will slowly add the generic stat upgrades, so they can't get chosen by ordinary level ups.

• Progression 1 - Health & Healing 1
• Progression 2 - Armor 1
• Progression 3 - Willpower & White Resist 1
• Progression 4 - Melee, Ranged, & White Damage 1
• Progression 5 - Speed 1
• Progression 6 - Health & Healing 2
• Progression 7 - Armor 2
• Progression 8 - Willpower & White Resist 2
• Progression 9 - Melee, Ranged, & White Damage 2
• Progression 10 - Speed 2
• Progression 11 - Health & Healing 3
• Progression 12 - Armor 3
• Progression 13 - Willpower & White Resist 3
• Progression 14 - Melee, Ranged, & White Damage 3
• Progression 15 - Speed 3
  

The above Mindwipe buff means Ianna's units will get even stronger at higher progression levels, so I'll skip a few progression upgrades for special buffs.

Note: The Astral Image Titan for Ianna is changed to 3 variants that deal White/Death/Fire damage.  They are immune to Physical and their element.

• Progression 6 - All units count as Dreaming and gain a random minor Dream at the start of combat.
• Progression 9 - The Dreamweaver's Sleep battle enchantment is applied to all battles.
• Progression 10 - Ranged units gain Inner Eye (+2 range).  Units gain a major dream instead of a minor dream at the start of combat.
• Progression 11 - Gets an extra Stackslot, bringing her total up to 8.  This slot is usually a Titan, such as an Astral Image of Fire/Light/Death.
• Progression 12 - Gets an extra Stackslot, bringing her total up to 9.  This slot is a Titan, such as an Astral Image of
  Fire/Light/Death.
• Progression 13 - Gets an extra Stackslot, bringing her total up to 10.  This slot is a Titan, such as an Astral Image of
  Fire/Light/Death.

• Progression 14 - All units get a Dreamweaver's Hat.
  

Isgrimm
To emulate the Artificer class' flexibility and power, Isgrimm can "equip" a nearly unlimited number of Glyphs onto his units.  These are unlocked over time as normal level-up options (providing bonuses usually reserved for the 3 major level thresholds), with higher "weight" being given to higher tier Glyphs.  Since these are tied to levels, which is tied to progression, some progression levels are skipped.

• Progression 5 - All units gain a special upgrade that unlocks access to Mountain-Copper-based upgrades.  Also grants Health, Healing, Armor, and Willpower stat upgrades.  Mountain Copper upgrades include: Bowman, Deathlord, Despair, Guardians, Healthy, Pathfinder, Rhino, Shield, Spider, Swordmaster, and White Mage.
• Progression 8 - All units gain a special upgrade that unlocks access to Sky-Iron-based upgrades.  Also grants Health, Healing, and Armor 2 + Elemental Resistance and Speed 1 stat upgrades.  Sky Iron upgrades include: Blight, Bowman, Deathlord, Despair, Elementalist, Lifegiver, Necromancer, Rhino, Shield, Swordmaster, Vampire, and White Mage.
• Progression 10 - All units gain a special upgrade that unlocks access to Corrupted-Adamantium-based upgrades.  Also grants Health and Armor 3 + Willpower, Elemental Resistance, and Speed 2 stat upgrades.  Corrupted Adamantium upgrades include: Ashen, Bowman, Cutthroat, Deathlord, Eel, Firewielder, Healthy, Rhino, Spider, and Swordmaster.
• Progression 11 - Gets an extra Stackslot, bringing his total up to 8.  This slot is a Titan, such as a Forgemaster.
• Progression 12 - All units gain a special upgrade that unlocks access to Adamantium-based upgrades.  Also grants Healing, Willpower, Elemental
  Resistance, and Speed 3 stat upgrades.  Adamantium upgrades include: Arcanist, Ashen, Blight, Bowman, Cutthroat, Deathlord, Elementalist, Guardians, Healthy, Leader, Occultism, Rhino, Shield, Spider, Swordmaster, Vampire, and White Mage.
• Progression 14 - Titans gain +50% HP, +5 armor, +5 willpower, +10% damage, First Strike, Total Awareness, Agile, and Effortless Defense.
  

Raith

• Progression 8 - Units gain Corrosive Attacks (-1 armor per hit) and Exhaustion (-2 damage in 2 radius on death).  2x Dark Elf Necromancers appear as enemy reinforcements in all battles.
• Progression 9 - Battles are enchanted with Chaotic Weapons, randomly changing the damage type of every unit.
• Progression 10 - Battles are enchanted with Silenced, affecting 1 random target each turn.
• Progression 11 - Gets an extra Stackslot, bringing his total up to 9.  This slot is a Titan, such as a Flesh Colossus.
• Progression 12 - Battles are enchanted with Separate Plane of Existence, causing non-Fantastic units to deal -50% damage.
• Progression 13 - Battles are enchanted with Entangled, Staggered, and Dazed, each affecting 1 random target a turn.
• Progression 14 - Another 2x Dark Elf Necromancers appear as enemy reinforcements in all battles.
  

Rohen

• Progression 9 - All Spellcasters are given the Bribery skill, which mindcontrols Followers.  All non-Spellcasters are given the Emancipation skill, which mindcontrols Slaves.
• Progression 10 - All Mortal units gain Appetizers.  All units get Slayer.  All Orcs and Trolls get Gladiator.
• Progression 11 - Gets an extra Stackslot, bringing his total up to 9.  This slot brings an increased variety of Trolls to his armies.
• Progression 12 - Gets an extra Stackslot, bringing his total up to 10.  This slot is a Titan, such as a Treant, Forgemaster, Shaper Golem, or
  Lightbringer.
• Progression 13 - Battles are enchanted with Divided Battlefield, causing player Titans to deal -75% damage to non-Titans and player non-Titans to deal -75% damage to Titans.  Heroes/Apprentices are not affected.
• Progression 14 - All units get Pack Tactics.
  

Undergast
Note: The "summon on death" abilities are implemented as a single-tile AoE revive (same skill type as Alpha Wolves use to summon Wolves).  The summoned unit seems to only appear on an adjacent tile.  And there may be some edges cases where weird things will happen.

Note: Getting Infused Memory at Progression 7 is a significant buff to Undergast's forces, since all his units are Fantastic, so I won't give him some progression upgrades.

• Progression 9 - All units carry minor research material which is dropped on death.  These are summons such as a Sealed Fire/Ice/Nature Elemental, Tier 1/2 Demon, Chaotic Wisp, Fire Spirits, or Alchemy/Runesmith/Necromancer minions.
• Progression 10 - Gets an extra Stackslot, bringing his total up to 7.  This slot brings a Golem, such as a Fire Golem, Ice Golem, Blood Golem, or Stone Golem.
• Progression 11 - Gets an extra Stackslot, bringing his total up to 8.  This slot is a Titan, such as a Shaper Golem.
• Progression 12 - All units carry important research material instead of minor research material.  These are summons such as a Fire/Ice/Blood/Stone Golem or Tier 3 Demon.
  

Uram

• Progression 6 - All demons get Occult Incantations.
• Progression 9 - 2x Sacrificial Cultists appear as enemy reinforcements in all battles.
• Progression 10 - Gets an extra Stackslot, bringing his total up to 8.  This slot is a Titan, such as Demonlord Sa'Hrul or Rav Ozeal.
• Progression 11 - Gets an extra Stackslot, bringing his total up to 9.  This slot is a Titan, such as Demonlord Mrask Dur or Krahz Al'Guh.
• Progression 12 - Gets an extra Stackslot, bringing his total up to 10.  This slot is a Titan, such as Demonlord Azra'Zil.
• Progression 14 - All demons get Demon Kin.
  

Yria
To emulate the Alchemist class, Yria's units gain random buffs at the start of combat that grant passive buffs and active abilities.  These are randomly chosen from a small pool at the start of combat, with units losing 1 AP per potion (as if they actually used a potion).

• Progression 7 - Melee units gain either Finon Beer, Blood Mead, or Mindnumbing Elixir at the start of battle.  Ranged units gain Eagle Spirits instead.  But units lose 1 AP at the start of battle.
• Progression 8 - All units gain either Earth Armor Elixir, Dwarven Forgebrew, or Draught of the Giant at the start of battle.  But units lose 1 more AP at the start of battle.
• Progression 9 - All units gain either Leeching Elixir (not ranged units), Potion of Regeneration, or Allfire Essence at the start of battle.  But units lose 1 more AP at the start of battle.
• Progression 10 - Melee units gain either Dancers Potion, Poison Coating, Firebloom Coating at the start of battle.  Ranged units gain Arcane Concoction instead.  All units gain Potion of Undead Control and Love Potion.
• Progression 11 - Gets an extra Stackslot, bringing her total up to 8.  This slot is a Titan, such as a Lightbringer or Treant.
• Progression 12 - All units gain Bandages, Lenya, and Potent Water, making them immune to Bleeding, Poison, and Burning.
• Progression 13 - Melee units gain either Plague Vessel, Potion of Firebreathing, Sacred Water, or Toxic Distillate.  Spellcasters gain Revitalizing Nectar.
• Progression 14 - Battles are enchanted with Raining Vials, putting lots of hazard tiles that inflict resistance debuffs on the player only.
  

Note: Yria's unit pool is expanded to include an Elven Druid, which deals elemental damage, has a Wolf bodyguard, and mind controls animals.

Other Changes
This mod also modifies a few existing items, to rebalance them for this mod.  These items are ones that particularly trivialize the game, so rather than increase the difficulty to account for them, changing them makes more sense.

• Corrupted Glyph of the Leader - Now reduces damage of the unit by 30%, but all Followers gain +3 damage.
• Level 3 Paradox Demon - Execution threshold reduced to 25%.
  

• Mindcontrolled units now have a hidden tag that prevents them from being enslaved. This should only affect Ianna's units, but there may be exceptions that I haven't thought of.
• Demon Lord Azra'Zil had his Chaotic Weakness is tweaked to change every turn, because I noticed it was possible he would remain immune to damage for multiple turns (possible bug with the status effect trigger).
• Followers (promotion), Haunted Armor (unit), and Dwarven Combat Balloon (unit) are given a tag specific to them.  This is to better assign unit effects in the mod and should have no other impact.
• Parry Stance now replaces Fortify.  Parry originally lacked the 20% damage reduction of Fortify, so you had to make a choice between the two defensive stances.  Since it now has the same damage reduction, it never makes sense to use Fortify if a unit has Parry.
  

Note: This mod adds a couple unsupported Unity References in the .odl files.  This means certain parts of the mod will not work after any update to
the game.  I'll document them here, so I don't forget how to fix them.

• Skills/Support/Summon*.asset.odl -- uses the "SkillEvaluation" Unity Reference found in Skills/Support/CellDivisionSkill.asset
• Units/Promotions/BriberySkill.asset.odl and EmancipationSkill.asset.odl -- uses the "SkillEvaluation" Unity Reference found in Skills/Magic/MindcontrolSkill.asset
• Units/Promotions/Yria/PlagueVesselSkill.asset.odl, SacredWaterSkill.asset.odl, and ToxicDistillateSkill.asset.odl -- uses the "SkillEvaluation" found in Skills/Magic/MeteorSkill.asset
• Most of the new units added in this mod do not have certain sound effects, because those are all Unity References.  Since the presence or absence of sound effects does not have any gameplay impact, I opted to remove them instead of requiring an extensive fix each update.
• Units/Factions/Humans/Tiara_Priest.asset.odl -- must copy the "Considerations" into Units/Factions/Ianna/Tiara_Priest.asset.odl