i wanna know if its more worth it to run imperial instead of nord for a build im planning that even without the nord passive, decisive, and normal ult generation from normal actions take would have roughly 18.3 ult gen per second if you make sure to pop a siphoning ability every 4 seconds and a dawns wrath ability every 6 and im wondering at that rate is it better for a roughly 200 ult cost spell especially with the 5% ult cost reduction already from dawns wrath to go imperial or is ult cost reduction stacked just not worth it cause i think if it works the way i think it does it would still work but i wanna know for sure because i imagine it works multiplicitivly like this;

if your ult costs 200 and you have 2 seperate ult cost reductions of 10% and 5%, it adds them like 10% of 200 = 180 and than 5% of 180 = 171 but is it instead additive meaning that instead of 171 it would be 170 because 10% of 200 is 20 and 5% of 200 is 10 because if so than ult cost reduction is more worth it to stack than i had thought but if not than i think i will just go with imperial and dawns wrath and call it that because i already hit the diminishing returns for the most part.