Enemies' spell slots - Larian Studios forums
The issue with Divination is how limited spell slots are in 5e, but you get a fantastic ability in this subclass that circumvents that.
How do you feel about the Eldritch Knight?
The only way an Eldritch Knight would gain 9th-level spell slots is by multiclassing into a full caster class (wizard, druid, cleric, bard, sorcerer).
Wizard Spell List - 5th Edition SRD
5th Edition (5e) Wizard spell list, organized by level.