Nut: I didn't know this was a thing. I jumped straight to the Mana Shield section and saw that there's some pseudocode explaining exactly how it's calculated and how it's applied. Such detail. Jarulf's Guide is a keeper.

I remember Mana Shield being OP a.f., and according to this guide, it actually got nerfed in Hellfire in a weird way, where increasing the spell level also increases the damage taken.