Letter from Duke Luca Abele is the title of two different written notes found in Dishonored 2.
My marvelous Alexandria Hypatia! Or do those closest call you Alex?
How valuable you are to me! To Serkonos! What would we do without one of our most prominent Natural Philosophers? It keeps me awake at night, worrying for your safety. What if some incurable wretch should attack you? Or what if exposure to one of those hideous maladies you come across proves fatal to you? Where would we be then? Who would we turn to?
So you see, that is why I have arranged for the Grand Guard to keep an eye on your offices at Addermire. For now, indulge me. As your Duke, I recognize your value, and I am committed to keeping you safe!
Duke of Serkonos
This note can be found on Hypatia's desk inside the Addermire Institute during the mission The Good Doctor.
Smart of you to agree to host this special little party. It will do much for your social standing, and I knew I could count on you. Be careful not to muck it up!
Here are some of the particulars. More later.
We'll need a locked room. Locked. That's very important because we don't want your servants entering at a sensitive moment and ruining everything. Nor would we want any of the guests to leave! No windows or if there must be windows, then perhaps make certain they are heavily draped?
Once everyone has been made comfortable with refreshments and such, it is crucial your servants and security retreat for the night! They must not interfere! Send them home if you must, or to the streets if they have no residence.
As for guests, I believe there will be five of us. Including you. No surprise additions please! If someone stops by, send them away! This is to be a private séance, and the guests have been especially chosen by Breanna Ashworth. You don't want to displease her, do you?
I hope I've made these instructions clear. You were my father's closest friend, and I know the old badger would be happy that you're helping me with this matter.
The note can be found during the mission A Crack in the Slab, on Stilton's desk in his bedroom in the past.