I had something similar happen on my first 5 mask two weeks ago. I got cocky and pulled a second add with the Trade District boss (chain dude), somehow screwed up all the madnesses at once, failed the chain mechanic, and got stunned under the boss. By some miracle, the extra add I had pulled died and procced Gift of the Titans with 14 Sanity left.
I also blew my free rez by screwing up on the dude below the Mage Tower. That guy sucks on Leader Feet week...
One thing I've learned from doing Mage Towers is that (with our cloaks at the level they're at now + Gift of the Titans), you're MUCH more likely to die from rushing than from Sanity loss. Enter with a goal in mind, and play with the objective of completing that goal. Once you've got a route down and your upgrades unlocked, there's no point in making risky moves to try to optimize your Sanity.