A legendary hammerdwarf (with full steel armor and silver war hammer) first went into tantrum like everybody does sooner or later in a fort without any luxuries. Her husband and several pets may have died shortly before. In her rage, she knocked the head off some peasant, calmed down, got imprisoned, repeated the whole thing when she got out again and finally went berserk after being caught in the rain during patrol duty. She was pretty much the best, my militia had to offer, a dwarf that could take on entire sieges alone... so you can imagine, what happened next. Almost the whole military (none as good as her) was knocked out and about 10 civilians (of 60) dead. She only stopped when she dodged off a ledge after I commanded the whole fort to Zerg rush her. Ok, it wasn't just some ledge but the central spiral ramp that went down another 15z or so.
Afterwards, there were another few tantrums that could have ended badly as the military was dead or dying. Luckily, they mostly destroyed lots of furniture and calmed down again. The manager/broker and 3 other dwarves went insane, but not berserk, so the whole situation was rather relaxed for dwarven standards. The fort went on for about another decade before I got bored.
Yeah, I know it's not a true dwarven tantrum spiral until everybody is dead, but I had lots of Fun. And I absolutely loved how a little rain pushed the hammerdwarf over the edge of madness. Sure, it wouldn't have happened, if she was happier in the first place, but I can really imagine the situation: "Oh, it's raining again, as expected in a rain forest. I cant't stand this anymore! HULK SMASH!"
But I learned to important things from this episode:
1. Build luxurious prison cells that match a noble's room. If somone gets imprisoned for throwing a tantrum, you want them to gain some happiness. Fast.
2. Keep an eye on your military to see if everyone's at least content. It rarely matters if the baron or a fish cleaner throws a tantrum, but if a hammerdwarf feels like playing golf with heads, Fun will ensue.