The following self buffs are confirmed to be adding to the Critical Severity/Combat Advantage portion of the damage formula, rather than being a multiplicative buff in the buff category of damage.
-Trample the Fallen
-Battlerage (the mechanic)
-Vengeance above 50%
(yes, I rechecked these today, still bugged)
The following self bugs are confirmed to be on live
Coincidentally (or not so coincidentally?), the known instances of the bug are on all the classes that @asterdahl
handled in the Mod 16 rework (GF/GWF/DC). I am gathering all the bugged self buffs I know into one thread so asterdahl doesn't need to go into separate threads to figure out what's going on. If he wants the proof, the bug reports listing the bugs are linked below.
I do note that not every self buff was mentioned on these classes. I didn't have the patience to check those other buffs, but I would bet they are bugged by being additive to CA/Severity as well.
Individual Threads of Proof:https://www.arcgames.com/en/forums/neverwinter/#/discussion/1250926/barbarian-damage-bonuses-buggedhttps://www.arcgames.com/en/forums/neverwinter/#/discussion/1250399/pc-fighter-bugs-self-buffs-incorrectly-calculating-heavy-slash-tooltip-incorrecthttps://www.arcgames.com/en/forums/neverwinter/#/discussion/1250929/pc-doomslayer-and-divine-equilibrium-additive-instead-of-multiplicative