Preface:

I'm still new to modding, so please bear with me if you find any bugs. I'll do what I can to fix them as they appear. So far, the only thing I've found that seems buggy is that when a party member dies, it sometimes keeps them active, meaning you have to manually change the active party member to continue combat. It's hardly invasive since it only takes an extra second to click their portrait, but it's still odd. I don't see how anything from this mod could be causing it as opposed to it being Larian's coding, but if I find a solution for it, I'll update it.

Purpose:

This mod does several things:

• Removes the DeathSavingThrow passive from all characters, meaning if you drop to 0 HP and have nothing that will bounce you back up (Death Ward, Relentless Endurance, etc.) you will die instantly.
  

• Restricts resurrection spells to only work outside of combat.
  

• Adjusts base HP and HP per level for each class (exact numbers detailed below). NOT INCLUDED IN MAIN MOD ANYMORE (SEE UPDATE 1.1 BELOW).
  

• For fun, I gave everyone musical instrument proficiency and the ability to whistle.
  

By itself, I don't think this mod makes too drastic a change to the game, but when combined with any or several of the difficulty boosting mods found on Nexus, it can add a lot more tension to a battle.

This mod was created with the intention of balancing out mods such as Party Limit Begone and Unlocked Level Curve. Both of those mods don't give much of a boost early on, but help your party become exponentially stronger as the game progresses. Most other mods that increase difficulty don't really account for those first few levels where you are running a relatively normal-sized party and are maybe only a level or two ahead. IMO, it makes the beginning of the game, which I already found to be the most difficult part in vanilla, the most brutal.

For this reason, I gave a 50% boost to the base health of each class (12>18, 10>15, 8>12, 6>9), and reduced the amount gained per level by 50% (7>3, 6>3, 5>2, 4>2). Constitution modifier is still added each level. This will likely take some more tweaking. I may very well come up with a version that boosts base HP even more and completely removes class based HP per level gains.

Compatibility:

This should be compatible with any mod that doesn't tough ClassDescriptions.lsx, Origins.lsx or the Teleportation_Resurrection spell.

ClassDescriptions.lsx was edited only for the HP base and per level changes. I can add alt versions that include things like no spell preparation, deities for all class, scroll learning for all classes. Ideally, I can create a passive that reduces health and add it to Origins.lsx so I don't have to touch ClassDescriptions for future versions.

Origins.lsx was edited to remove the DeathSavingThrow passive, add the Perform passive (allows whistling when proficient with musical instruments), and add instrument proficiency.  In theory, these alterations could be applied to classes, races, or backgrounds. I just found more mods that touch those files, so editing Origins.lsx seemed better for compatibility purposes.

The Teleportation_Resurrection spell was given the requirement "!Combat" which restricts it to only being used outside of combat. As far as I could find, all other resurrection abilities use this spell as a base, so they pull over the "!Combat" requirement.

Installation:

Install using BBG3 Mod Manager

Load Order:

• As of now, load order doesn't matter between main files and add-ons. Only use one of the main files. Only use one of the add-ons.
• Load order doesn't matter between the modular files and add-ons. You can use one or both of the modular files. Only use one of the add-ons.
• There's no reason to use either of these modular files with a main file. Both modular files are contained within the main files.
  

Update 1.0.1:

Fixed a couple of errors: one that allowed Wyll to still make death saving throws and one that reduced the base HP of Rogues by too much.

Per request, I added a second version of the Main mod that removes all resurrection scrolls and removes revivify from all spell lists. I removed the scrolls mainly through editing the treasure tables and starting equipment. I ran into an issue with Shadowheart still having a resurrection scroll, even through it wasn't in the equipment file. I noticed the artefact isn't in there either, so it seems there is another file that adds additional items to her starting inventory. To work around this, I changed resurrection scrolls to Aid scrolls, which should affect any I may have missed. 

I also made a new add-on for further reducing HP per level. It increases the base HP of each class by 150%, but limits HP gains through levelling to only use your CON modifier.

Update 1.1:

Due to an issue causing Halsin and Minthara to die before even getting to interact with them, I've taken HP reduction out of the main mod. I left it in the add-ons since it can be installed later. From my testing, it only causes Halsin and Minthara to die if you have it installed before escaping the Nautiloid. If you install it AFTER reaching the ravaged beach, they should be okay. I tested this by installing the mod and loading the autosave that's created after you wake up at the beach.

The other Act I companions are unaffected by this mod, so I'm not entirely sure why Halsin and Minthara are. I haven't come across any other NPCs affected by it. It could theoretically affect later companions/NPCs. My suggestion for now if you'd like to use HP reduction would be to disable it before proceeding to a new act, saving once you reach the next act's main map, exiting the game, reenabling HP reduction, and loading the save from the new map.

I'm working on another method of HP reduction that'll hopefully avoid the issue entirely. I'm sorry to anyone that lost time due to this issue.

Update 1.2:

There's a new download titled "Deadlier Combat - Alt Version". I found a new way to reduce your party's HP without killing Halsin and Minthara off-screen. It also doesn't touch the ClassDescriptions.lsx file anymore, so mods that allow all classes to learn from scrolls, have a deity, or require no preparation for spells should be compatible now.

This version can get pretty brutal if you run with a big party. Each party member has a constant aura that reduces their HP and all surrounding party member's (aura radius is 300 meters) HP by 5%. The game rounds up, so a 20HP max means a reduction of 1HP per party member, and a 21HP max means reducing 2HP per party member. The reduction can bring your max all the way down to 1HP should you have the party size to bring it that low.

In order to get this to work right, each playable character (Tav, Origins, Hirelings) has a unique aura specific to them. Using the same aura cancelled each other out in my testing. Due to this, it won't work correctly playing multiple Tavs or Durges in one party. You'll only get one instance of each of their auras affecting the party. In theory, if you have a 12 member party, and 3 of them are Tav, you'll have 10 instances of reduction instead of 12.

In response to a request in the comments, I made it compatible with Appearance Edit Enhanced, as long as you load Deadlier Combat below Appearance Edit Enhanced. If requested, I can make the other versions of this mod compatible, as well.

If anyone knows how to hide status effects, please let me know. It doesn't personally bother me, but I can understand someone being bothered by having a dozen extra status conditions visible in multiple places.

Side note: after long resting, you may only see one condition on each character (reduction from their own aura). If you leave camp or reload, the rest show up. 

One last thing: if you're really a glutton for punishment, you can combine this with Deadlier Combat - Reduced HP, Add-on - Further Reduced HP, or Add-on - Scroll Scribing for All (only use one of these mods). Those 3 only touch the ClassDescriptions.lsx file. Be sure to read the warning regarding those add-ons detailed in Update 1.1 above.

Update 1.2.1:

Removed status icons from HP reduction in the Alt Version.

Update 1.2.2:

Added Alt Version Light. This version boosts each character's HP by 20%, then reduces it by 5% for each companion in their party. The goal was to have a 4 person party even out.  I initially used a 15% boost, but since the game rounds down on positive percentages and rounds up on negative, I went with 20% instead. You're normally within a hit point or 2 of where you would be without the mod in a 4 person party.

I also added an uninstaller for the alt versions to the miscellaneous files. Please follow the steps below to uninstall the mod completely:

• Uninstall whichever Alt Version you are using.
• Install the uninstaller mod.
• Load your game and long rest. This should clear the statuses that cause HP reduction.
• Save your game and exit.
• Uninstall the uninstaller mod.
• Load your last save to confirm it isn't crashing.
  

Plans for future mods:

Alternative growth system: This would be more akin to a Souls game where classes only affect starting abilities, equipment and stats. There would be more levels and increased ability caps to compensate for there being no gain to HP outside of your Con modifier. Instead of getting class specific features, levelling is only for gaining feats. There will be way more feats built off of existing class features (Rage, Martial Arts, Sculpt Spells, Destructive Wrath, etc.). I'm looking into requirements to create something of a tree system. For instance, if you want to take the Mindless Rage feat, you'll need to have the Rage feat.

Alternative alternative growth system: Pretty much the same as above, except you learn everything from scrolls. I could blend the two ideas.

Milestone levelling: This would likely take a lot of playtesting to truly balance. It's easy enough to adjust experience rewards so that you only gain experience from certain battles/quests. For instance, you can set it so that you gain enough XP to level when you escape the Nautiloid or when you kill the goblin boss at the first Druid Grove encounter. The trouble here is figuring out the perfect spots to gain levels, and sorting out what most players are likely to do within a playthrough.

Enemy Death Saves: This was something I initially worked on as an alternative challenge. Instead of taking death saves away from the player, I granted them to all NPCs. The problem is I don't know AI editing well enough to make NPCs actually use the Help action I created for them or heal their downed allies. I came up with an alternative solution where downed NPCs roll a d20 at the start of their turn (separate from death save), and if they roll a 10 or higher, they get healed. One drawback I found is that if an enemy dies by failing their final death save, you don't get any XP. It does create an interesting balance act where you need to time your hits on downed enemies to ensure they die so you don't lose the experience for it.