Alright, so I've given an earnest crack at reverse engineering some scripts, and this is where I've gotten so far. I've commented out some functions I'd like to use but if the behaviour of the function is even possible, I have no idea which functions I would use to achieve them. I potentially could try to find such functions through calling the names I'd think they'd have, then do trial and error; but trial and error with the txt files where I was simply interchanging values that I knew were valid was bad enough. Trial and error here would be pretty much unfeasible due to the time required.

(I think the problem before was that no matter what I do, the effect of the damage entry in potions is only applied when the CONSUME happens)

Shadow Mark:
Base.charScript

EVENT Severe_Bleeding_Tick
ON
OnTurn()
VARS
CHARACTER:_StatusSource
//INT:_Damage
ACTIONS
IF "c1&c2"
CharacterHasStatus(__Me,CONSUME,SevereBleeding)
CharacterGetStatusSourceCharacter(__Me,CONSUME,_StatusSource)
THEN
PlayEffectAt(__Me,"FX_Skills_Rogue_ShadowStrike_Impact_Male_A")
CharacterConsume(__Me,SevereBleedingDamage,1,1) //would like to remove
//CharacterGetDamage(_StatusSource, _Damage) //***
//Multiply(_Damage,x)
//CharacterTakeDamage(__Me, _Damage, "(Shadow/Piercing/None)")
ENDIF


Potions.txt

new entry "ShadowMark"
type "Potion"
data "DamageType" "Piercing"
data "StatusIcon" "statIcons_MarkOfDeath"
data "StackId" "SevereBleedingStatus"

new entry "ShadowMarkDamage"
type "Potion"
data "Duration" "1"
data "Damage" "10"
data "Damage Multiplier" "1175"
data "Damage Range" "0"
data "DamageType" "None"
data "StatusIcon" "statIcons_Remorse"


***Perhaps just dex scaling with CharacterGetStat(_StatDexterity, _StatusSource, Damage)? I'm also considering trying to store the damage dealt by the initial shadow step through an OnDamage(_,Damage,_,_) - but I'm not sure if I'm able to store variables with a global scope


As for the Coup de Grace, I'm wondering if an earlier idea I had that I wrote off as un-implementable would actually be more feasible? Just a quick yes or no if you think this is possible, you've already put so much time into helping me.

I wanted to have stacks build up on an enemy as I backstab them, and when at 3 stacks I could coup de grace them - same problem of having a non-scaling massive damage effect after the coup de grace goes off. If I change the perspective and have it say... Build up stacks on my character as I backstab and then at 5 stacks unlocks coup de grace for casting - I know I could get the stacks to build up, the problem is if:
1) I can identify backstabs, I don't see even a way to identify crits anywhere
2) Set coup-de-grace to castable after 5 stacks

I'm thinking maybe I could set the AP cost to what I want it to be onturn if there are 5 stacks, then remove the stacks once it is cast, and have an onturn that if <5 stacks, it's 99 AP. Or set the damage to 0 if less than 5 stacks. I'm not sure if I'm able to manipulate the damage multiplier of an ability, or the ap cost in a script is the problem. I don't see a way to, and I definitely don't see a way to flat out disable the skill.