So my thought is that to truly value all these mastery amulets, we should have dual school spells. These spells should be more powerful than an equivalent pip single school spell. So for example you could have burning frost which is 4+4 (4 fire pips + 4 ice pips). It would inflict 600 fire damage and then 500 ice damage or maybe a little less damage but add some other features (i.e. DOT, AOE, blades, traps, etc...). But the idea is that if either school tries to use this spell without a mastery amulet, they have to use 6 or 7 of their pips spots which at these higher levels often count like 12 or more pips since the powerpip percentages are so high. But if they have the corresponding mastery amulet they can cast using only 4 powerpips. I think this dual school spell idea can really lead to some awesome ideas.