Math post spoiler alert
Ok reduction of spell power seems is boost/1.3 rounded to tenths of %, not a 30% reduction in truth it’s only 23%.
Then research seems to boost HP correctly giving visual HP of dragon (if gear shows visual I don’t have any on the dragon im testing).
30% research boost is Base x 1.3
Consumable buff of 30% gives 23%, which if you remember from spell reduction is the “30% reduction” but this time it’s the boost amount.
30% consumable is visual HP x 1.230769
Edit: Been corrected by others and makes more sense, consumable buff adds HP equal to Base HP x 1.3 to visual Hp.
The above worked for my test, more to come (edit: confirmed for Tarand roar and also Lethal Barrier), but want to see if this works with anyone else.
Now the confusing part.
Expert Khrysos 30% research, no gear.
2662973 Base HP x .05 roar = 133148 Observered pre scale damage
.05/1.3=.0384… = .038 new spell scaling %
2662973 x 1.3 = 3461865 Visual HP
3461865 x .038 = 131550 Post scale damage, 30% HP buff from research did not equal pre because of the rounding above
3461865 x 1.230769 (1/1.3 the way they do a spell reduction = .769231, .230769 is 1-(1/1.3)) = 4260756
This is the 30% consumable adding HP above visual HP.
Edit: 2662973 x 1.3 = 798892 + 3461865 = 4260757
4260756 x .038 = 161908.7, I observed 161908 Post scale damage with 30% HP consumable
Edited for better punctuation and readability
Edit: If they stated spells as 23% and some change reduction, because as such 30% buff makes pre to post equal. Also, 30% consumable as times by 1.3 instead of 1+(1/3), 1.23 and some change, it would be correctly stated and hopefully a lot of confusion cleared.