Starting Health Changes

Custom Races
When the Patcher detects a custom race, it, first, looks at its Behavior Data file to figure out what race it is based on.

For instance, if it has "GiantProject.hkx" it will assume the race is copy of the vanilla Giant Race or another race in vanilla that uses "GiantProject.hkx". The original race of a custom race is decided upon by comparing the custom race's Starting Health, Magicka, and Stamina to all other vanilla races using  "GiantProject.hkx" . Then amongst the races, the one with greatest similarity is determined to be the original race. After that Requiem values of the Original Race's attributes (health, unarmed damage, etc.) are copied over provided that they are greater than the attributes being patched.

On Dragons
Requiem changes the starting health of of the DragonRace record in the vanilla game from 500->7000.
Then for for most, if not all,  Dragon NPCs, it appears that the health offset they had in vanilla was multiplied by exactly 0.3.

So Requiem - Auto NPC Patcher takes this exact approach to balancing mod added dragons as well.


Health Offset Changes

For what I consider "static" NPCs the formula is as follows:
If  a new NPC has the same health as NPCs from its derived vanilla race then:
New Health Offset = Requiem's Health Offset for that Race

However, if the NPC, for instance, is stronger than its vanilla counterpart then:
New Health Offset  = Difference in Mod's offset compared to Vanilla  + Requiem's Health Offset for that Race

This ensures that, at minimum, the NPC will be brought up to Requiem's stats and if the Mod Author's intention was for NPCs of the new race to be stronger than the their vanilla counterpart,  that will be reflected in the Patch as well.

For NPCs in the "Scaling" group, (playable race NPCs) it is more complicated. Requiem - Auto NPC Patcher uses an in-game spell to distribute health to NPCs based on their Class and level. The value I decided on after analyzing Requiem NPCs is 5.5 health per level for weapon users and 3 for pure magic users. As such an NPC is only on trend when their health offset out of game is set to 0. Therefore, if the patcher detects that a new NPC's Health Offset is below the trend associated with its Class it sets it's health offset to 0 out-of-game so it will be bumped up to the trend in-game via the spell but not be above it.

If Requiem - Auto NPC Patcher detects that NPC is above its class' health gain trend, It wants it to retain it's health above the trend but not gain more than that. So it decreases it's out-of-game offset to:

New Health Offset  = Mod's Orignial Health Offset - ( Patcher Defined NPC's Class Health Per Level * NPC level-1)


Via the rebalancing spell, all NPCs gain, by default, 3-5.5 health per level depending on their class, so this NPC is still above trend in-game.

If "Make New Creatures Stronger than Playable Races" is enabled in the patcher, then NPCs that use a custom race derived from a playable race will not have their out-of game offset reduced. Many creature mods use copies of playable races for their new creatures. For example, Mihail's Minatours, Gravelords, and Goblins are all copies of playable races but with custom models. In vanilla Skyrim, the majority of generic NPCs from playable races lack Health Offsets. Therefore, for custom races derived from playable races, I interpret any value in their health offset as how their mod-author intended them to be relative to playable races.
By not adjusting these NPCs out-of-game offsets, they receive the full increase playable-race NPCs get via the patcher's health spell on top of their offset and thus the mod author's design for the NPC is kept but readjusted to fit with Requiem.


Information on how these spells are distributed is available in the article "NPC Class and Race Keywords and SPID Distribution".

Auto Calc Stats/PC Level Mult Changes

In Skyrim, NPCs that have the flag "PC Level Mult" or "Auto Calc Stats" gain Health every level according to this equation:

Class Health Per Level = (10 * (Level-1)) *(  Class Health Weight / (Class Health Weight +  Class Stamina Weight + Class Magicka Weight)

(In Requiem the 10 in the formula is brought down to a 5 as well.)

Almost every NPC in Skyrim has one if not both of these flags whereas, in Requiem, almost no NPCs have these flags. 

To account for this, every NPC patched by Requiem - Auto NPC Patcher that has these flags receives a spell via SPID that subtracts the same amount of health gained per level granted to it via AutoCalcStats so that the Patcher's main Health Calculation spell (which is based of the health per level trend in requiem) can have full control over the NPC's health.


Magicka & Stamina

Approaches similar to those above are used to balance the starting stats and offsets for both Stamina and Magicka.