Mana reseration on "Flesh and stone"

I have: 2 x 8% inc mana reseerv, 12% inc mana reserv and 15 % inc mana reserv from passive skills.
As example, pride and determinations mana reserv goes down from 50%->34.97%, okay. But Flesh and stone goes down from 25%->22.73%. Dread banner goes down from 10%->6.99%. First two and last aura, real mana reserv reduction is about 30% but in case of Flesh and Stone its about 10% of starting value. Why?

nvm, just found out linked chaos dmg increased mana cost, mb