Ok, I'd like to rescind my previous cynicism and propose an actual hypothethis for the existence of the kill phrase.
I don't buy that Lenore is suicidal, because people with suicidal ideations don't make long term plans or set long term goals. She might have felt lonely and depressed but she still kept on going with her research. She even planned a trip to Baldur's Gate and likely went through with it.
My hypothesis is based on two facts. 1) Lenore built a way for her automaton to kill her. 2) She had the exact ingredients in her lab to brew Omeluum's potion.
Hence my guess: Lenore was infected by a tadpole, but found a way to keep it in stasis, effectively stopping the ceremorphosis. However, she knew things could go wrong and decided to install a failsafe into Bernard. Should she start feeling the symptoms, she would say the phrase and have the automaton stop her heart with a single, painless blast of electricity.
After all, that's the exact strategy Nettie suggests with the Wyvern potion.
Hmm.
So ideation is only the first stage. Lenore is well past that, and everything about her does scream warning signs. (The more specific the plan, the greater the danger.)
That said, I really like this theory.
In fact, this is probably the strongest theory I've heard to date.
