Apply Hope to 6 large bones surrounding Yeppa's Last Stand
Stand next to the bone and use the potion from either your hotbar or inventory (Note: the bones do not highlight, and are not clickable, just stand next to them and use the potion.)
Note: the originally discovered "evil" bone behind Yeppa is, somehow, NOT curable. Since the quest is broken, and required bones do not light up, enjoy your time-sink.
If you can't safely access the bones outside of the camp, wait (approximately 5 minutes) and the timer will reset for the bones that are safe to access, allowing you to reapply Hope to them again
