Board Thread:Speculation House/@comment-34633327-20180125034140/@comment-4141313-20180216094416

73.Anon.52 wrote: ^If she's immortal like Oz, she wouldn't have had to take it to get it from Cinder... just wait out her natural lifespan. Or alternatively, like she did with Leo, let Cinder stick around until she proves too annoying to deal with. Since Leo losing his initial usefulness and general cowardice was enough for her to kill him, it would not be a stretch to think that she'd off Cinder if she proved too detrimental to the plans, especially if she can always take the powers herself.

She's made it clear people have their uses, so she could just let Cinder run around with the powers till her use ran out.