For example i have a skill that does 100 physical damage and somehow i can convert 100% to fire. Then does melee physical damage support gem count? Because i read on poe wiki they said damage conversion happens before any addictive and multiplicative to avoid double count. Thanks in advance
External link →The wiki is correct, in that all the modifiers are applied after conversion. This is important because it means they can all stack together correctly.
However, modifiers apply based on what type the damage is, and what type(s) was converted from. So fire damage that's converted from physical damage is affected by modifiers to fire damage and by modifiers to physical damage.
Importantly, all "increased" and "reduced" modifiers to a value stack additively (this is the stacking part I mentioned before). This means that if you have 100 physical damage, and convert 100% of that damage from physical to fire, then if you have stats granting "10% increased physical damage", "10% increased fire damage", and "10% increased damage", those all apply to that damage, but becasue they're all increases, they sum together to a total 30% increase and apply together, resulting in a total of 130 fire damage.
This is different to if the physical increase applied before the conversion and the fire one afterwards, which is why it has to work this way - letting them apply at different times would make them work as multiplicatively stacking modifiers, which would be much more powerful.
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