Okay, if you insist. The New Mutant appearances and Firestar minseries which established the power struggles within the Hellfire Club and the lengths to which she would go to maintain her power and control in that group; training Firestar purely as an assasination weapon should she need Selene killed.
Her interactions with Magneto during their time as rival headmasters. With Emma being the one to help the New Mutants deal with the death trauma the Beyonder put them through, but NOT pressing her advantage.
The entire two or three issue X-Men arc where her mind possesses Iceman's body, uses it in many novel and interesting ways that Iceman had never had, as she goes looking for the Hellions, and goes into some detail about how she recruited them and the lengths she had gone to protect them (finding them without (at least at first) access to a Cerebro, making sure they were invisible to Sentinel tech etc) and her desolation and self loathing when she discovers they really ARE dead and died protecting her. The real start of the road to her redemption.
The Generation X stories where she was headmistress, perhaps most notably the one where the deaths of the Hellions are replayed in her head with the GX crew filling the roles the Hellions had.