bezoar

similar to a trichobezoar, I suppose

Probably. People pay plentiful pennies for Potter publications.

Perusers of Potter publications are probably plotting pranks as we speak.

(Yes, I cheated on publications. Whatcha gonna do about it?)

Poppycock!

Perhaps Potter partygoers are pooped. It's perfectly possible.

And pickling peppers, perchance?

Yes, the Potter patter is petering out.

I'm with u. I'm all Pottered out.

More like Harry SNOTTER! Hee hee, I'm so witty. ;-)

Harry Potter uses one of these in book six. (Sorry u, it's not over yet.)

Sounds like something that would kill you before the poison did. Blecch.

I'm not familiar with the lord-satrap aspect, but it seems remiss not to mention the physical properties of a bezoar:

a hard indigestible mass of material, such as hair, vegetable fibers, or fruits, found in the stomachs or intestines of animals, especially ruminants, and humans. It was formerly considered to be an antidote to poisons and to possess magic properties

A related concept is that of mithridatism, which is the building up a tolerance by taking a series of gradually increasing doses over a long period of time until very high doses are tolerated.
(Warning! Don't try this at home: it works for only certain types of drugs/poisons, depending on the nature of the primary toxicity).
Mithridatism plays a key role in 'The Princess Bride', also in a very well-known murder mystery by ... well, better not to risk being a spoiler

protector from poison (harm): antidote: similar to lord or satrap