A couple of ideas I tossed around before mostly settling on the Djinn are:
- Geomancer. Control over stone and magma. You could make stone prisons, throw lava rocks, and cause miniature volcanic eruptions. Subclasses could focus on either fire or earth manipulation.
-Frost Knight. A Paladin substitute without healings, it would be a heavy armor class that focuses hardcore on battlefield control
-4 Elements. Expand on the basic idea of the Monk subclass but... better. Not sure what direction subclasses would go.
-Elementalist basic control over 4 elements with subclasses focusing on different elements providing a lot of the real meat of the class. Maybe a spellcasting base class? A real cool mechanic would be that partway through class progression, you either choose a second subclass to start benefitting from, or you choose a second element and combine them into a new one (Fire+Earth=Magma, Air+Water=Storm, etc)