Curse Magnitude Scaling???

I don't want to spoil my build idea too much but I am curious about how Curse Magnitude works in regard to scaling the damage of curse support gems such as impending doom or decaying hex.

I am hoping that through scaling curse magnitude I can also scale the damaging effects of the support gems attached to the curse itself but it's quite confusing because obviously in most cases the damage is either a chaos hit or a chaos DoT... made even more confusing by the description of the effects on the support gem (for instance impending doom states the "Doom Blast" Hit has the base damage of 15% of whatever your current Mana is (*hopefully at the time of casting and not after the cast consumes the mana) which implies the scaling mechanism would be stacking mana. However Decaying Hex considers the players total intelligence as the base figure for chaos damage over time...

And then of course there is the most confusing support of them all which is Hayoxi's Fulmination which I don't even want to begin explaining because there are quite a few different avenues for scaling based on what curse is supported... if you want to scale the spell hits, the elemental damage. it's very confusing because in a certain sense it obviously would scale with curse magnitude because for instance if you use despair, the magnitude determines how chaos resistant the target is which obviously makes the hits larger due to lower enemy resistance but more importantly... does it scale the base damage numbers as well.

I guess I spoiled my build idea but... How does curse magnitude work in this context? Am I just over thinking this? Help!