Aura support Scion vs Guardian vs Necromancer

Hi i plan to create a weird build that would have high rarity and quantity, would have good clear speed of maps (t8-t12 with possibility to do all maps even t16 but maybe with not so good clear speed) and with all that would be tanky (more the better).

Idea is to play as caster (spell not sure yet maybe frostbolt maybe spark will see) and use low life rf.
Only 2 classes i see have potential to do that are necromancer and guardian with some special unique's and stacking allot auras to cover most of defense and give an edge in offense. Now looking at scion i see he have 12% attack and cast speed while affected by auras you cast (as guardian spec) and 15% increased damage while affected by auras you cast (as necro).

I know Necromancer's commander of darkness and Guardian's unwavering fate give their bonus by number of auras they give. Scion have a little bit different wording (i know words are important) than Templar and Witch where their buff say Auras you cast grant "insert buff here" and Scion say "insert buff here" affected by auras you cast.

In both case they say AURAS so does Scion also gain buffs per aura or only for having aura?