Blessing of vitality?

Hi guys, i was just wondering... in the description of blessing of vitality it says "reduce mana cost per level" if i can remember correctly - but are we talking about the mana cost for THIS spell only or for all spells? i mean, it gives HP regen for melee types, but does it give us an advantage? (less mana per spell)

Just the spell in question. The blessing of might spell has the same benefit. Also ressurection