Nether Magic

The first character is a Psionic Sorceress, she has psionic powers (such as telekinesis, telepathy, mind control...) and magic powers (spell casting, magical energy projection...) and the second is a inexperienced Neowitch empath wielding Aether Magic and Nether Magic. What powers could go well for a third character to complete this trio? I am planning for the character to appear weak at their first appearence but grows powerful along the time. So what power could fit them well?