How can I make a high level magus fail a will save?

We are playing an epic level campaign in which all PCs and most NPCs are 20th level. This has been really fun but I am quickly finding that it is very hard to get an advantage over some of the people I am fighting.

I am fighting a 20th Level Magus with the Bladebound and Kensai archetypes and I need him to fail a will save. The DC on the will save is 25. I don’t know his stats but that’s not that great at all against a 20th level character of any type.

What spells/methods/techniques can I use to help him fail this save?

  • I have considered Mind Fog but he will most likely save against it.

  • I am playing a ninja but he insists that he is immune to being flat-footed, surprised, or flanked so I cant use my capstone to lower his wisdom (How the hell can he do this? I see Iaijutsu Master but the way I am interpreting that is that he always acts in surprise rounds. He can act all he wants if he doesn’t know I am there…!)

  • I have a 17th level Mindchemist/Psychonaut Alchemist cohort, but I cant seem to find anything good there that will help (although she is damn good at UMD and will be casting a scroll that is the reason I need him to fail this save).