This is the actual damage formula in the game's code (shared_battle_damage.lua, lines 59-60)
From what I thought I understood from reading the code and associated masteries,
>OriginalMultiplier is the total % damage increases from things like Sharpening and One-Inch Punch
>OriginalDemultiplier is the total % damage reduction from things like Forgotten Pain and Blade Evasion
>AdditionalDamage is literally only used by Fire SP and Ice SP (Ice SP gives negative additional damage)
>FinalMultiplier is literally only used for Miracle
>Crits are handled separately in a different part of the code
>so are "event damage" calculations, ie Magic Explosion, Special Armour and Magic Shield
Am I just misunderstanding the formula?