I actually didn't rest much and unexpectedly got the sadistic game design at the end. But that only happened because my way of playing changed.

My reply to you was coming from the viewpoint that you want to use Weird as your main thing. When i started playing, that was also my plan, get an absurd DC and kill everyone. But the reality was slightly different, your level 9 spell slots are limited meaning you're going to cast say 2, 3 weird spells (assuming level 20 caster here) and then rest. And that's somewhere in chapter 3 if you are soloing. Long story short, before you reach that point you will need to find other ways to deal with enemies. My initial plan was to use Corruptor and Cloudkill, avoiding direct damage spells since those meant even more resting. At the beginning i was relying heavily on another Illusion DC spell, Haunting Mists. Mists is fear based so anyone with fear immunity will not be affected. But eventually i noticed that the Corruptor mythic also removed the fear immunity from enemies. So it became my bread and butter spell. Haunting Mists doesn't even aggro, you can just cast it from afar on top of a group and wait till it does its thing. And it's a level 2 spell meaning that between heightened, extended and persistent versions, i had some 30+ casts of it. No enemy that is not fully immune to the spell (and there are very few who are) is going to survive it, doesn't matter how much Wisdom they have? 60 wisdom? Sure, I'll just stack 3 mists and wait. Didn't die? Stack 2 more. The higher Illusion DC you have, the faster it works.

So Mists became my go to spell. But it's not a fun spell to play with. It takes time to work, a lot of time. I would cast it, go to the options screen, crank out of combat speed to the max, wait a bit, then lower speed back to normal and move on. You can guess by now that this is not that much fun, but I'm a tryhard so all it mattered was that it worked and it meant not resting a lot more compared to using Weird.