Originally Posted by
Zaerix
Well she is alive, it's just that in Outland she used a generic dragon model so you couldn't see the scars afflicted upon her by Deathwing attempting to mate with her and being defeated by Korialstrasz.
Also, I'm not sure, but I believe BC takes place before she created the first Twilight Dragons, one of whom, Dargonax, destabilized during a fight with various dragons and lore heroes and burned away, taking Sinestra with him.
Whether she survived or died but was resurrected is up to speculation.