"
4L Alphas Howl (BBBB) - Blasphemy, Enfeeble, Temporal Chains, Enlightened Level 4 (12% Reduction)
Total Reserved Mana From Helmet - 35+35=70x0.40[Passives(34%), Alphas Howl(8), Enlightened(12%), Skyforth(6%)]=28%
The actual reservation is 32% here.
"
The total of all "Reduced Mana Reserved" modifiers whether from passives, jewels, or items, is summed before being applied. However "less" modifiers, and mana multipliers such as that granted by Enlighten Support inventory icon.pngEnlighten Support each apply as separate multiplications.
Source:
http://pathofexile.gamepedia.com/Mana_reservation
48% reduced mana Reserved = 34 (Passives) + 8 (Alpha's Howl) + 6 (Skyforth)
12% less mana Reserved (Enlighten)
70% mana Reserved (2 Curse Blasphemy)
70 * (1-.48) * (1-.12) = 32% mana Reserved
I would recommend using
https://poe.mikelat.com/ to figure out aura reservations.