Stirix

Stirix is a Night Hag, an Evil Outsider who was summoned into the Demiplane of Dread by Azalin to assist him with planar research. The task the King of Darkon set the Night Hag was to find a way to break him free of Darkon and the larger Demiplane. When Stirix was by all appearances unable to do so, Azalin cut her loose and banished her from Castle Avernus.

Only once Stirix was certain that she was free of Azalin's scrutiny, did she really start to work on developing a method of escape. Against all odds, she succeeded. Stirix' creation, the Rift Spanner, is a device powered by souls and capable of travelling between the Demiplane of Dread and the rest of the multiverse so long as it holds enough charge. Stirix has not yet departed, owing to a desire to taunt Azalin before she goes.