Every damage can be converted once. It’s like a drawing with a signature, once signatured you can’t do anything to take it off and leave the drawing without the signature in its original state. So basically, if you convert 100% vitality damage to physical, the converted damage has a signature of vitality damage but behaves like physical.
Vitality damage
Physical damage
Converted Vitality to Physical damage - as you can see it contains the same color as it had before conversion, this is the signature.
Now, if you convert 100% vitality to physical and 50% vitality to fire, you effectively convert 150% of vitality damage, but as conversion doesn’t increase your damage by any means, only changes the typing of the damage type, you’ll deal 75% of this vitality damage as physical and 25% as fire, because the game calculates the values as 100/150 and 50/150 where 150 is value of both conversions in one, 100 + 50.
The order for conversion as stated in the Game Guide is as follows:
Base Skill > Skill Modifiers > Conversion on the Skill or Transmuter > Conversion on Equipment and Buffs > Equipment, Auras and Passives
Tainted Power is a transmuter and Stormseer Sapphire/Aetherbolt Pendant’s conversions are skill modifiers. Tainted Power will hence go after the Amulets conversion.
Keep in mind that:
-For conversions that do 100% in one step (such as Stormseer Sapphire’s 100% Aether to Lightning) that there is no more Aether damage left to convert for following conversion steps (such as Tainted Power).
-Damage can only be converted once. You can use Aetherbolt Pendant to convert AAR’s Fire to Lightning but you cannot then use tainted Power to convert this new source of Lightning to Vitality.
Damage bonuses apply after conversion. In each example you specified, you want % Physical for the first and % Chaos for the last. % Vitality/Aether would do nothing for each respective case.
What if I had an item that added flat damage to an ability? Like let’s say “+ 20 physical damage”, would that damage come in before or after the conversion?
And what if I had “10% of weapon damage” to an ability? Would that damage be converted if the weapon does that type of damage?
For example, if I wore Mythical Essence of the Grim Dawn which adds +60 Aether damage to Aether Ray, and then used Tainted Power, would I end up with an Aether Ray that does Chaos Damage and Aether damage, or would the Aether damage be added on before the conversion?