Here is the link to Ultimate Difficulty Scaling mod:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3527530349
This mod is based on two great mods for difficulty scaling:

Level Scaling Challenge by Clangeddin
https://neverwintervault.org/project/nwn2/script/level-scaling-challenge

Personal Impossibility Adjustment by kevL's
https://neverwintervault.org/project/nwn2/script/personal-impossibility-adjustment

This mod merges and improves those two mods and provides highly customizable dynamic difficulty scaling by auto-leveling and enhancing enemy stats.

Without this mod, the original NWN 2 campaign is VERY easy and dull even on the official very difficult rules with 200% damage for enemies. Very easy I mean actually ZERO challenge especially on high levels.

With this mod every battle turns into an actual fight, not a slaughter of helpless infants. With this you''l finally get a real motivation to:

• Plan proper builds for the whole party
  
  
• Carefully select spells and abilities for each character
  
  
• Pre-buff before every fight
  
  
• Plan your actions 3, 5, 10 moves ahead

The result is a completely different experience from the original campaign – it's like playing a different game with real opponents, not a leisurely stroll where all enemies die in one hit...

BEWARE!

Default difficulty settings for this mod are pretty tough and require:

✓ Good party composition

✓ Good character builds

✓ Tactical planning

✓ Pre-buffing.

But, of course, you may always configure and fine tune all difficulty options just as you like: enemy level scaling, enemy stats enhancements and enemy pre-buffs.

UDS
Ultimate Difficulty Scaling
It's an acronym for this mod title for quick reference

2DA files
Special NWN 2 configuration and data files for storing information in a table form with column labels and row IDs. Often used as a convenient way to configure mods without recompiling them.

LSC
Level Scaling Challenge
It's an acronym for one of the base mods and components of UDS which checks and scales enemy levels. May be configured by 2da file and completely turned off.

PIA
Personal Impossibility Adjustment
It's an acronym for one of the base mods and components of UDS which enhances enemy stats. May be configured by 2da file and completely turned off.

XP
Experience

HD
Hit Dice
HD is a measure of relative power that is synonymous with character level for the sake of spells, magic items, and magical effects that affect a certain number of hit dice of creatures.
So, usually HD = creature's level.

CR
Challenge Rating
CR is a numerical representation of a creature's combat difficulty, with higher numbers indicating tougher encounters. It's a guideline, not a strict rule, and is used to gauge how challenging a monster will be for a party of adventurers with an average level equal to the creature's CR.

CR is based on a combination of offensive and defensive capabilities, including things like attack bonuses, damage output, armor class, and hit points.

It's important to remember that CR is a loose approximation. Many factors can influence the difficulty of an encounter, such as the number of players, their class builds, their tactical decisions, and the specific environment.

CR also defines amount of XP given for killing a creature which is also defined by average party level. Party get more XP for killing creature with higher CR closer to average party level.

For example, if creature with CR 7 is killed by level 10 party - it gives 50 XP, while if the same creature is killed by level 12 party - it gives only 11 XP.

• Is UDS compatible with Companion and Monster AI by Tony K or any other mods?
  
  Yes, UDS is compatible with Companion and Monster AI by Tony K.
  
  Please check the Compatibility section of this guide for more details.
  
  
  
• How does UDS work?
  
  I think it's better to show you an in-game log:
  
  
  As you can see, when you encounter, for example, a Githyanki Patrol mod gives you detailed info about the creature level and stats and how mod enhances them.
  
  1. Mod checks and shows HD (Hit Dice = Level) and CR (Challenge Rating) of the creature.
  
  2. Mod checks if level scaling (Scaled to PC level) and stats enhancement (Adjusted by PIA) are already applied to the creature.
  
  3. Mod executes LSC script (level scaling) and shows initial and scaled levels of the creature.
  
  4. Mod executes PIA script (enemy stats enhancement) and shows initial and enhanced stats with all modifications.
  
  5. Mod executes pre-buffing depending on configured buffs, level and type of the creature.
  
  
  
• Does UDS need a new game? May I uninstall and install UDS freely?
  
  No, UDS does not need a new game - you may freely install and uninstall UDS anytime.
  
  Although all creatures already affected by UDS: scaled levels, enhanced stats, pre-buffs keep their state after mod uninstallation.
  
  
  
• What should I do if enemy or encounter is too tough after being scaled by UDS?
  
  If the challenge is too high and you face an encounter that you can't win you have to go back to a previous save where enemies were not scaled yet and lower the difficulty settings or temporarily disable some or all UDS components.
  
  Or you may just use a godmode or script that kills the creature outright :-)
  
  It's really hard to make universal default difficulty settings appropriate for all type of the encounters.
  
  For example, arcane spellcasters are heavily pre-buffed by default difficulty settings. If there are only 1 - 2 arcane spellcasters (which is a case for most encounters) then their default pre-buffing feels ok and balanced. If arcane spellcasters (which are very squishy without buffs) were not pre-buffed that would make them too weak and mundane opponents while they should be quite the opposite. And it would be just not fair as player usually goes to fight with fully pre-buffed party :-)
  
  But if there are 3 or more arcane spellcasters against the player that can make things too tough. For example, during Qara Sunken Flagon encounters with too many arcane spellcasters at once. In this case pre-buffing option may be temporarily switched off by setting "22 EffectBuffs" to "0 **** ****" in your active difficulty.2da file. Default difficulty.2da should be in (mod folder)\Personal Impossibility Adjustment\difficulty\default\.
  
  Another reason to pre-buff enemy spellcasters is to make use for player of counter-magic spells like Dispel, Spell Breach, Mordenkainen Disjunction and so on. With UDS they become very useful measure against pre-buffed enemy spellcasters.
  
  
  
  
• When are enemies scaled by UDS? Will enemies scale before I start a fight from a distance or from stealth? What if tough enemies scale too early and I won't be able to lower scaling settings or disable scaling?
  
  UDS has a rather complex scaling system and tries to scale enemies before the fight starts but not too early that player has no choice of not scaling specific encounters or enemies or lower scaling options.
  
  UDS tracks 3 kinds of events: ON SPAWN, ON HEARTBEAT and ON PERCEIVED.
  
  UDS also tracks the distance to enemy from the closest party member or summoned creature. The minimum distance of scaling is 50. All creatures farther than 50 won't be scaled.
  
  Also, no enemies will be scaled after moving to a new area until your main PC changes position.
  
  This is made because during cutscenes game thinks your party is physically present there and looking from the cutscene camera (yeah, I know it's weird but that's it). So, the game tries to scale all creatures within cutscene even if they are far away in other location which definitely is not an intended behavior.
  
  
  
• Are friendly NPCs and creatures scaled by UDS? What if they become hostile during a dialog or a cutscene?
  
  UDS tracks hostility of all creatures around and scales level only (no stats enhancement or pre-buffing) for all friendly targets within scaling distance of 50. So, don't be surprised by messages about greycloaks also gaining levels after you level up your main PC :-)
  
  But if any creature suddenly becomes hostile even during a dialog or a cutscene UDS will almost immediately apply full scaling logic with stats enhancing and pre-buffing.
  
  
  
• I get more XP for enemies killed. Why? What if I don't want to?
  
  You get more XP because of enemy level scaling by LSC component - higher enemy levels increase their CR and hence give more XP.
  
  You may turn off level scaling by setting MAXI to 1 in (mod folder) \ Level Scaling Challenge \ LSC_options.2da file.

Mod is generally incompatible with other mods overriding:

• ON HEARTBEAT event handler: nw_c2_default1.ncs
  
  
• ON PERCEIVED event handler: nw_c2_default2.ncs
  
  
• ON SPAWN event handler: nw_c2_default9.ncs.

Manual merging of those files required for compatibility.


COMPATIBLE MODS AND UDS VERSIONS

There is a Companion and Monster AI 2.12 compatible version of UDS:

https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3528815356


Will update this section if more compatible mods appear.

To customize mod settings you need to open the mod folder:

(your Steam path)\steamapps\workshop\content\2738630\3527530349\override\UDS\

PLEASE NOTE:

Mod folder path will change if you use other UDS version like Companion and Monster AI compatible UDS version.


There are several folders inside, 2da files and Readme files.

Mod settings are configured by 2da files.

If you want to keep your mod configuration in case of mod workshop updates you have to copy configured 2da files in your local override folder:

(Windows user)\Documents\Neverwinter Nights 2\override\

You may create a "UDS" folder there for clarity.

PLEASE NOTE: Copy ONLY 2da files you've configured. DO NOT COPY other mod files or further workshop mod updates won't be applied.

Default enemy level scaling in UDS is 3 levels below your main character. I've tested it by myself in official campaign and level progression is faster but generally in line with increased enemy toughness and difficulty. And you may use your high level abilities sooner, not in the very end of the official campaign, especially if you play race like aasimar or drow with slower level progression.

PLEASE NOTE:
If you play any race with level adjustment like drow or aasimar it's recommended to adjust "1 ADJU" value in "LSC_options.2da" from default "-3" to "-2" for aasimar and other -1 races and "-1" for drow and other -2 races.

This is because your main character level is lower than usual and enemy levels will also be scaled to lower levels unless you adjust this setting.


UDS does not only scale levels but also enhances other enemy stats: attack, damage, AC, HP, saves, etc and also may pre-buff enemies with various spells. So, enemies in UDS are much tougher than in mods with just level scaling and this usually justifies increased XP gain.


Default values in difficulty.2da for enemy stats enhancement:

+1 increase to attack, damage, AC and saves of enemies per 2 of your main PC levels

+200% to current enemy HP (not per your PC level).

It's pretty tough enemy enhancement but manageable if your party composition, character builds and tactics are good enough.

Level scaling is configured by:

(mod folder)/Level Scaling Challenge/LSC_options.2da

Here are the options with their IDs, default values and descriptions:

0 MAXI

Default: 160

The maximum level of the scaling mechanic in absolute.
Cannot be higher than 160.
Cannot be lower than 1 as local variable.
Set to 1 to switch off level scaling.


1 ADJU

Default: -3

The maximum level that enemies can scale up to compared to your owned character.
For example, if you are level 8 and this value is 1, enemies will scale up to level 9. If it's -1, they will scale up to level 7.
Cannot be equal to 0 as local variable.


2 FEEDBACK

Default: 1

If set to 1, a detailed message will provide info on what level the enemy scaled to and in which classes they gained levels.


3 ENEMYONLY

Default: 0

If set to 0, scaling will apply ONLY to enemies. Experimental, use at your own risk, certain npcs that become enemies after a dialog will not scale up at all.


4 LOWLVL

Default: 0

This is low-level max level limit for low level content. If set to >0 this will reduce the value of ADJU for characters of levels lower than LOWLVL.


5 LOWLVL_ADJU

Default: 1

by an amount equal to LOWLVL_ADJU


6 PROP

Default: 100

Proportional scaling.

Considers the gap between the PC level and the enemy and uses a percentage of it to scale up the enemy.

For example, with the default value of 80, if the PC is level 20 and the enemy is level 10, the enemy will be scaled up to 18, as 20-10=10*80/100=8. Values lower than 1 or higher than 99 will disable this feature.

Enemy stats enhancements are configured by difficulty.2da files in:

(mod folder) / Personal Impossibility Adjustment / Difficulty /

Difficulty.2da is a user-editable text file that controls how tough to make Monsters and NPCs.

These are the variables in Difficulty.2da that you should set to your preferred difficulty. Note that every Module or Campaign that's publicly available tends to have its own balance. The OC tends to be very easy, while there are 3rd party Modules and Campaigns that are very hard. So, usually you need different difficulty.2da files with different difficulty settings.

You can create folders per Module/Campaign and maintain your personal Difficulty.2da files for each here.

IMPORTANT: Don't forget to disable all difficulty.2da files in "(mod folder) / Personal Impossibility Adjustment / Difficulty /" by changing the extensions to ".2d_" except for the one that you wish to currently enable and use. The game always load only ONE file with the same name and extension and all other files are ignored.

For your convenience difficulty.2da files are included for the OC, MotB, and SoZ. Change their values as you prefer.

Recommended strategy for new modules is to set up difficulty.2da settings to zero and start the Module or Campaign with hardest NWN2 difficulty. Then make saves, push up the values in difficulty.2da, and reload the Module or Campaign repeatedly until you feel that the challenge is about right.

Stats enhancement values in difficulty.2da may scale depending on creature CR, your main PC level or be fixed - it's a matter of your choice.

COLUMNS

Value

Stat bonuses depending on CR that is calculated as:

(2da value * creature's Challenge Rating) / 20

So, creature get full bonus if it has CR

PCLevel

Any of the "per 20 CR" bonuses can get an extra bonus depending on main PC level.

It works like this: The value that you set for PcLevel represents how many levels the PC Leader needs to have before creatures get an extra +1 bonus. This bonus will be added as-is whether there is a "per 20 CR" Value or not.

bonus = PcLeader's level / 2da val

For example if PcLevel is set to 1 creatures will get a +1 bonus PER LEVEL of the party Leader - in other words do not set it to 1 unless you want to scream, pull your hair out, run away in frustration and get an arrow for 300 pts in the back of your character. However if set to a value of 6 a 12th level Leader would generate only +2 bonuses or if set to 5 a 15th level Leader would generate +3 bonuses, etc. The resulting bonus will be rounded down. You should understand that this is an inverse relationship before using it.

Negative PCLevel as a fixed bonus
If you make PCLEvel negative it becomes just a plain fixed bonus not depending on creature CR or main PC level.

AddRand

Any of the "per 20 CR" bonuses can get an extra bonus between 0 and the value specified (inclusive). This bonus will not be scaled but added as-is whether there is a "per 20 CR" Value or not.

ROWS

0 Active

1 turns the PIA on, 0 is off.

1 PrintInfo

0: No feedback printing for quiet operation.

1: Displays a lot of info in chat as the Pia processes any creatures. Note however that this info often fails to print when the party is entering a Module or area. You'll get a lot of data about the strengths and weaknesses of Monsters and NPCs, and you'll know if the Pia is installed correctly. This can help with fine-tuning the values in Difficulty.2da to your own playstyle and desired challenge. Info will be sent only to the Leader of the party. A value of 2 prints the info to NwN2's logfile instead if you have NwN2's logging turned on. The logfile can be found at AppData\Local\Temp\NWN2\LOGS\nwclientLog1.txt

3: Turns on both 1 and 2.

2 MapAbilities

Use Primary Ability mapping.

1: Enables Primary Ability mapping.

The Primary Ability bonus values that you set in Difficulty.2da will be mapped to Primary Ability bonus 1, Primary Ability bonus 2, Primary Ability bonus 3 ... through Primary Ability bonus 6.

PIA will then rank the creature's Primary Abilities from highest to lowest where StrBonus is mapped to whatever Ability is determined to be Primary Ability 1, DexBonus maps to Primary Ability 2, ConBonus maps to Primary Ability 3 ... and ChaBonus maps to Primary Ability 6.

0: Turns ability mapping off.

Strictly speaking this means that if you turn Primary Mapping on you should order or rank the values from highest to lowest in the following order: Strength, Dexterity, Constitution, Intelligence, Wisdom, Charisma. The StrBonus value now becomes the bonus to whatever Primary Ability the Module designer has set as the creature's highest Primary Ability down through the ranks until the ChaBonus value becomes the bonus to whatever Primary Ability the designer set as the creature's lowest Primary Ability. Hence a lich with a high Intelligence gets its biggest bonus to Intelligence and a Rogue-like creature with a high Dexterity gets its biggest bonus to Dexterity and so on.

3 - 8 StrBonus to ChaBonus

Primary Ability modifiers.

NOTE:

Strength increases attack and damage;

Constitution increases HP and also Fortitude Save;

Dexterity increases AB for creatures with Weapon Finesse wielding light weapons, AC if armor permits, and Reflex Save;

Intelligence increases Save DC of arcane casters;

Wisdom increases Save DC of most divine casters, and Will Save;

Charisma increase Save DC of other casters, including Warlocks, Bards, and creatures with special abilities.

9 HpBonusPct

The bonus hitpoints that creatures get as a percentage.

100 mean 100% and doubles current hitpoints of a creature with 20 CR.

10 AcBonus

Increases dodge armor class.

11 AttackBonus

Increases the attack of Monsters and NPCs.

12 DamageBonus

Increases the damage delivered by Monsters and NPCs.

13 AttackBonus_nat

Increases the attack of natural creature weapons.

14 DamageBonus_nat

Increases the damage delivered by natural creature weapons.

15 HandEnhance

Weapon and Shield Enhancement Bonus.

This affects creatures that are equipped with weapons (not natural weapons) or shields but only if a creature has them in its hands when the script runs. It is not a bonus per se; think of it as the minimum magical enhancement of opponents' weapons or shields. If the weapon or shield drops when the creature is slain you get the enchanted item(s).

16 SaveAdjust

Saving Throw modifier.

This either increases a creature's saves or, if negative, lowers a creature's saves.

17 SRBonus

Increases spell resistance. A fix for broken SR on items (esp. creature carapices) will be applied regardless of the value chosen. Also note that the stock engine does not do SR checks properly for persistent Area of Effect spells.

18 SrUseHd

1: Grants a creature spell resistance equal to its hitdice if greater.

19 CraftLoot

1 to enable the Pia's OC-style crafting material drops.

20 CraftLootPct

Affects script that generates OC-style crafting drops: gems, materials, OC essences. The chance to generate loot is equal to a creature's HD plus this value, which can be negative. Try a value of about 10 if you want it on. Note that more than one item can be generated, with each successive drop having a chance equal to the creature's hitdice.

21 CdaLoot

PIA can call cdAulepp's Random Loot Generator:
https://neverwintervault.org/project/nwn2/script/cdaulepps-random-loot-generator

0 (default) off; 1 to turn it on if you have it installed. If you want to configure cd's RLG do it in his scripts; the Pia calls 'fw_random_loot'.

22 EffectBuffs

1 enables Pia_SpellEffects.2da (see below); 0 to disable.

Enemy pre-buffing settings are configured by pia_spelleffects.2da file in:

(mod folder) / Personal Impossibility Adjustment / spelleffects /


IMPORTANT:
All effects are of permanent duration.


PLEASE NOTE:
The 3 Feats (SpellPenetration, SpellFocus, Concentration) are special in
that they are not spell effects. Only the CastFactor col is considered for
Feats and they can be applied only to Arcane/Divine casters.


CastFactor

The values in this col are treated very similarly to the per20cr values in
Difficulty.2da - they are per20hd in that the level of a buff is calculated by
the following formula:

cast power = (2da val * creature's HitDice) / 20

That is, if you specify "20" the cast power will be equal to the creature's
hitdice; lower or higher values will be calculated appropriately (rounded down).
For a creature to receive a buff from a category the cast power needs to be
equal to or higher than the minimum spell level in that category. For example,
the category "MageArmor" will cast MageArmor if the resulting cast power is
greater than or equal to 1 since MageArmor is a first level spell; but
ImprovedMageArmor will be cast instead if the resulting cast power is greater
than or equal to 3 since ImprovedMageArmor is a 3rd level spell. The spells in
each category are listed in the Description col along with their level - note
that the Innate level is considered per Spells.2da.

If a value of "0" or less is specified, a category is bypassed.


ArcaneStep

The values in this col influence the cast power (calculated from CastFactor) if
the creature is determined to be an arcane caster. But unlike the multiplicative
CastFactor value, this value is merely additive: you can straightforwardly shift
the cast power up or down by this value.


ArcanePct

The percentage chance that an effect will be applied according to the rules
above. If a value of "0" or less is specified, the category is bypassed.


DivineStep

As ArcaneStep but for creatures that are determined to be Divine casters.


DivinePct

As ArcanePct but for creatures that are determined to be Divine casters.


MundaneStep

As ArcaneStep but for creatures that are *not* casters.


MundanePct

As ArcanePct but for creatures that are *not* casters.


Visuals

A value of "1" applies the standard spell visuals to a creature if they are
available - not all spells have visuals. A value of "0" will apply the effects
without any visuals.


Dispelable

A value of "1" allows the effect to be removed by dispel magic (or if the
creature rests). A value of "0" applies the effect as Supernatural, which means
that the effect can be removed only by scripting.


SpellId


Do not change values in the SpellId col unless you know what you're doing. The
SpellId is made available in case you need to resolve conflicts with other
spells per Spells.2da.


Description

Lists the Innate spell level(s) of the spell effect per Spells.2da. The cast
power (see CastFactor above) + the Step value (see above) needs to be equal to
or greater than a spell's Innate level before it will be applied.