yes mp cost are scale to mp pool, but for the last 2 expansions they had to fix SCH Adlo and Succors we were being over charged for less effect. HW they lessen it, then SB they lessen it more and adjusted the shield. they have a formula for mp, but when it came to SCH the formula never worked for it plus they nerfed the mp returned form Atherflow. they gave us Lucid dream but it sucked compared to the mp i was getting back from Atherflow, we would get double of what LD would gives us in LD cooldown, this was needed since Sch spells has the biggest cost.