Turning to Diamonds

Stress level 3 is the cap, and Björn Ironside (867, Wrath of the Northmen) is the speedrun: he's Honest, so starting Murder schemes stresses him out - queue up ten of them back to back and he rockets from zero to a shattering mental break in one sitting. Cancel them all afterwards, no harm done (to you). Stressful Situation falls out en route if you don't already have it.