If you have played through most of the main story and have Wyll in your party, you will find that Mizora can be quite a pain in the rear.
During Act III, she makes multiple appearances and later visits your camp after a long rest following the ceremony held at Wyrm’s Rock Fortress.
This causes her to provide Wyll with a choice of sacrificing himself for help in searching for his father, who has been taken away, or breaking free from his contract.
How To Start The Encounter?
This encounter with Mizora happens at your camp once you have decided to take a Long Rest but only after you speak with her, later after Duke Ravengard is transferred.
You will need to progress to the point where you encounter Gortash in the ceremony at Wyrm’s Rock Fortress, where he is coronated as the Archduke.
After this happens, you may find Mizora outside and speak with her before making your way to the Lower City and she mentions that she will visit your camp later.
Should You Free Will Or Save His Father?
Sacrificing Wyll For Duke Ravengard
If you choose to gain information on the whereabouts of Wyll’s father, this will forever bind Wyll to Mizora with an eternal contract.
This results in Wyll never being free of Mizora and is an exchange that he is willing to make to save his father for the future of Baldur’s Gate.
Freeing Wyll of His Pact
If you decide to break the pact, Wyll will be set free from Mizora but this leaves Duke Ravengard’s fate in danger.
Choosing this gives you the chance to save Duke Ravengard, but even if you are successful, Mizora will appear and attempt to have him killed but this is also something you can interfere with.
Verdict
Deciding to have Wyll break the pact seems like the best choice here since you can always head after his father to save him. (This happens at the Iron Throne)
Mizora will be accompanied by infernal arbiters (Cirrus and Feena), which is proof that this time she plans to hold her part of the bargain.
You will want to make sure you make your way to the Iron Throne later when you reach the Lower City if you want to help Duke Ravengard and reunite him with Wyll.