I’ll keep it short with an example:
Item A applies 50% phys to lightning conversion on skill x.
I have Item B which converts grants a global 50% phys to lightning conversion.
I understand item A’s conversion will occur before item B’s conversion.
Will these 2 things stack additively to grant 100% phys to lightning conversion on skill x?
Or will item B convert 50% of the remaining 50% to yield a total of 75% phys to lightning conversion?
If item A’s conversion is a skill modifier, then this will happen.
Thanks baka. 
http://www.grimdawn.com/guide/gameplay/combat.php#q20
you see that skill modifiers goes before other conversions
That makes sense. Just wasn’t sure if the effect was multiplicative or additive.
It is always multiplicative, imagine if you have 3 conversions say skill modifier, skill transmuter and global conversion with 50% conversion in each step. Your total conversion would be 0.5 + (1-0.5)*0.5 + (1-(1-0.5)*0.5)^0.5
I too have yet another question on conversion mechanics.
I just found this item and was curious how it works.
It converts Lightning to Pierce and Physical to Lightning. Question is, in what order do these conversions occur? Afaik a specific damage type can only convert once, so I guess Lightning is first converted to Pierce, THEN physical is converted to Lightning so you end up with unconverted Lightning even if the item rolled 100% Lightning to Pierce conversion. Or am I missing something?
They occur at effectively the same time.
With the stat rolls on that weapon, you’d have leftover Lightning that can be converted because of the Lightning->Pierce conversion, Pierce damage that can’t be converted, leftover Physical damage that can be converted because of the Physical->Lightning conversion and Lightning damage that cannot be converted again.
If you had 100% Lightning->Pierce conversion, you’de have Pierce/Lightning damage that cannot be converted again and leftover Physical damage that could be converted further.
Also a question regarding conversion, does the damage from celestial powers get converted when attached to pets if the pets have damage conversion?
Foe example, say you have 100% cold > chaos for pets. Do you get chaos Whirlpool, Blizzard etc if you bind them to pets?
Also what about pseudo pets like Nemesis? I am guessing the player’s conversion will be used in that case?
Conversions on the same level are additive, on the different - multiplicative. Item skill modifiers and skill transmuters are on same level, elemental conversion has a priority over fire/lightning/cold.
Yes.
Interesting
What about player scaled pets?
Player’s conversion work for them)
I see. Ty 
This rule always applies to all conversions: damage can only be converted ONCE
This may confuse newbies (talking about myself, since I had this doubt).
While it is true, it should be noted that once, means your 100% damage can be converted only once. But 1 thing converting 30% of your damage and another thing another 30% and then another 40%, counts as once. So you could say each “unit” of your damage can only be converted once.
At least this is what Ive understood, correct me if Im wrong.
I don’t understand what you’re saying, but I’ll take a stab at it.
Assume I have 100 physical damage.
15% is converted to cold damage (i.e. starpact)
10% is converted to aether damage (e.g. seal of corruption)
This 10 now-converted-to-aether damage cannot be converted back into cold damage, even though starpact is active.
What is confusing is this -
Assume I have a demolitionist which does and only does 100 fire damage.
I have 90% Elemental to physical conversion, courtesy of octavius set + spellscourge set.
I now put on voidheart - 25% fire to chaos.
This conversion is occuring at the same level.
I think I’ll convert 90% of my fire damage to physical first, and then convert the 25% of the remainder to chaos damage.
But I can’t say for certain.
Can anyone confirm?
As Korsar stated before, elemental damage takes precedence to individual fire/lightning/cold in the conversion order. So it would be logical for it to happen the way you described it. Then again, haven’t tested it myself, so i guess we’ll have to wait for a confirmation.
Btw, welcome back, i wasn’t signed as a user when you were active, but i always enjoyed your posts on the forum
It’s good to be back.
Im still new at this, but for what Ive read, conversions of the same level (in this case, items converting a non skill specific damage type) are applied scaling the percentajes.
So if you try to convert 90% and 25% of a damage type, it will scale 115% (the sum) to 100% and apply the respective scaling to the 2 percentages:
you would convert 78,26% to physical and 21,73% to chaos
EDIT: Im talking about what happens when you convert over 100% of the damage, not taking the elemental vs fire of the original damage into account
