Hi,
maybe i’m blind but what is “damage with burning”? Is it damage to burning enemies? When yes, why is the bonus constant at 60% even if i equip paragon nodes with this wording?
Damage over time does not apply either, right?
Ok, i’m townblind. Bonus is shown outside of town. 
Thx for answering.
Damage with Burning is a buff specific to the Fire DOT effect or Incinerate/Firewall.
Damage to Burning is any damage you deal to targets that have a Burning Damage effect on them. Like you could use Fire Bolt to apply burning and then Chain Lighning to benefit from the Damage to Burning modifier.
Combustion will only receive bonuses from affixes that are worded as “+Damage with Burning”. “+Damage over time” affixes do not work with Combustion even though they do increase the Damage with Burning in the end.
I think only the Tourch glyph buffs Combustion now days.
Figured out and went into depth on what’s wrong with the Combustion tooltip here: Post Patch - Sorc Combustion Key Passive - #18 by Childe-1683
Basically, there are two issues:
The “Damage with Burning” bonus on the character sheet is miscalculating. It’s using the following formula:
[ (DamageOverTime + TorchGlyphBurningDamage) x (100% + Burning Instinct Multiplier) x (100% + Aspect of Conflagration) ] + Burning Instinct Multiplier
So it’s not including Endless Pyre at all, and it’s bizarrely using Burning Instinct both as a multiplier (correct) and as an additive value after multipliers (incorrect).
The Combustion tooltip is also miscalculating. It’s using the following formula:
60% + ( 25% x [ TorchGlyphBurningDamage x (100% + Aspect of Conflagration) + BurningInstinctMultiplier ] )
So it’s ignoring the “Damage Over Time” affix and Amethysts, inheriting the incorrect additive use of Burning Instinct, ignoring Burning Instinct’s actual multiplication, and also ignoring Endless Pyre.
Just did some calculations and found the right numbers, at least according to my character.
I believe that Combustion only benefits from Torch and Burning Instinct. (And an extra bug)
So the numbers on my Combustion are:
If we add the values of Torch (bonus 58.9) and B.I. (bonus 22.5) when they are alone, we get 81.4 . Which is very far from the bonus of 134.3 that we have when both are active.
The difference is 134.3 - 81.4 = 52.9 . This extra value comes from the B.I. node being applied to the Torch Glyph… So if B.I. multiplies the burning damage by 0.9 and we get the Torch bonus of 58.9 and put then together we have 58.9 * 0.9 = 53.01.
The difference between 53.01 and 52.9 is because the Torch bonus is rounded up on the tooltip, in my calculator it match perfectly.
In other words, the combination of Torch and B.I. is double dipping with Combustion. (I assume it is a bug)