This really isn't helpful to people in actual toxic work places or abusive situations. Appreciate your efforts but this article provides little value to most people.
Arsenic. Or peanuts if he's allergic to peanuts. Watch the old Alfred Hitchcock TV shows. Lots of ideas.
I had many good bosses during my working life of over 45 years. There was only one which kept me up at night, worrying as to whether he would allow me to do my job. He was of the type who wanted to control everything. He would say, for instance, this week I will control such and such. When that was my unit, it practically put me out of business for the week. We were State Employees, and we knew our jobs and were good at them, but he threw a kink in our operations just to show that he could. He was using us as stepping stones to get to where he wanted to be. Of course, we realized that, and just sucked it up until he had made his year and moved on.