Because you get more vs mal than you get vs spell?
Even if you get more saves vs. Mals, the saves vs. Spells stack onto it. Like I posted above, if you have -40 saves to Mals and -15 saves to Spells, it's basically like having -55 saves to Mals. And being the fact that it takes into account both saves, the help file basically says that it's combining the two saves together. Hence why I'd like to know why Pali would choose Mal saves over Spell saves when they're the same thing basically just that the Spell saves also stack onto the other saves you have not just the one.
