"Skills Cost Life instead of 30% of Mana" and "Non-channeling skills have -# to mana cost"

A user has reported an inconsistency regarding mana cost of skills on the Path of Building Community Fork:
https://github.com/PathOfBuildingCommunity/PathOfBuilding/issues/6008

Using Toxic Rain + Supports with a base mana cost of 37, a total of "Non-channelling skills have -21 to mana cost", and the new "Skills Cost Life instead of 30% of Mana" mastery, they achieve a final cost of 11 mana + 11 life.


If the mastery is to be applied before the -21 mana cost, they should get 26 mana (70% of 37), reduced to 5 when adding -21 cost, and 11 life (30% of 37).

If the mastery is to be applied after the -21 mana cost, they should get 11 mana (70% of 16 (37-21)) and 5 life (30% of 16 (37-21)).

Instead it seems that the life portion is calculated before subtracting mana cost, while the mana portion is calculated after subtraction. I believe both portions should be calculated simultaneously.

bump. the mana and life part are inconsistent result to a high than expect cost after the -# flat mana on jewelry.

"

Mark_GGG wrote:

No modifiers to Mana Cost affect the Life Cost. They only affect the Mana Cost
Modifiers to Cost affect both parts of the cost.

in game is functioning correctly, POB is calculating it wrong.

ignore proper math order for this, left to right calculations(to lazy to format properly)

mana cost 37 x 1 -21 x .7 = 11.2
life cost 37 x 1 x .3 = 11.1

the conversion isn't a reduced cost calculation.

e: link to thread with marks post https://www.pathofexile.com/forum/view-thread/3375759