Fun subclass! I've got a fewquestions though:
1) Is it on purpose that chromatic orb is on the noncombat spells list? Because I can't see how that could be interpreted as anything other than a combat spell...
2) The phrasing of the 15th level class feature is a little unclear. When exactly do you roll the chaos aura die? Is it when you are attacked (as a reaction?) or whenever you want to cast a combat spell?
3) How does this work in terms of action economy? For instance, if my sorcerer uses her bonus action to do something and then decides to cast a spell as her action and rolls on the table...and the roll ends up being a bonus action spell, what happens? Does the spell just become an action instead, or does it just not happen? What about spells that have casting times of 1 minute or more? If someone rolls one of those during combat, they're basically screwed bc of how many rounds that will take to cast. If I might make a suggestion: It might be a good idea to have separate tables for action spells, bonus action spells, and spells with longer casting times...