Spoilers below:

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* Sarek's gasses as a whole, Disintegrol is effectively MadeOfExplodium bottled and weaponized. A single drop of Krok poison turned its inventor into a [[BodyHorror hideous bloated hippo-man]] and would have dissolved him had the dose been larger. But especially "Sarek's Last Word," which attacks the nervous system, causing its victims to walk around in circles before dismembering themselves.
* His Under World in particular, a chemical lab so frightening that Faux-Hitler is afraid to see where his favorite toys are made.
* Ultimately, you get to the ending of the story. Sarek and Feuerbauch meet with Dr. Necros, who explains the details of a horrible new gas. He goes on to explain that it's effectively perfect and penetrates everything. It's creator bursts into tears as he explains his masterpiece can't be contained and they've all been exposed to it. Immediately after they learn that fact, they realize that Feuerbauch is walking in circles. They spend their final moments in a giddy, half-mad celebration of their impending deaths and begin to drink the Disinegrol. Feuerbauch's final thought is the compulsion to rip off his fingers.
* The resulting explosion of the lab turns a city into a mile-deep pit.