For my current Reign of Winter campaign, I'm going to be replacing large pieces of book 3, as I'm not a fan of much of the book. My plan is for the party to meet up with the Rashalka centaurs. The Rashalka are going to be bound to Baba Yaga's service through an ancient pact their ancestors made with her. Essentially, they were once human, and their tribe was decimated by raids from other tribes that rode horses. Desperate to survive, the Rashalka bargained with Baba Yaga to make them greater than horse riders. Baba Yaga struck the bargain, turning them into centaurs and binding them to her service until <something>.
I don't know what the <something> is. I want this to reinforce the fairy tale themes RoW has going through it, so something abstract yet still tangible. The players are going to be entering the Thrice Tenth Kingdom, and while there, I'd like for them to be able to assist the Rashalka in freeing themselves from Baba Yaga's service by finding the trigger for <something>.
The best I've come up with so far is they'll be bound to her service until they "find that which you gave up." Then in the Thrice Tenth Kingdom, the party finds an enormous pile of bones - all human legs. It's workable, but a little too literal for my taste.
Anybody have any ideas that would work for this?