How Dying Sun works?

So it works like GMP for all skills, adds 2 projectiles with less damage, or each projectile deals full damage?

Dying Sun does not reduce the damage of your projectiles.

So with spectral throw and slower projectiles, the extra 2 projectiles deal full damage each meaning u can do 3x more damage on boses if every projectile hits? (which is not hard for endgame boss hitbox)

Triple damage is unlikely with Spectral Throw, as there is a 0.3 hit cooldown per attack.

If you're looking to have the additional projectiles provide greater single target damage, you need overlapping area effects - I would imagine Molten Strike would be the best candidate for this, but you probably still wouldn't get triple damage.

Why i still can't run the 3 aura's even though I already have 2 nodes of reduced mana reserved?