I'm not liking the look of this so much. The appearance of another circle archmage looks like an excuse to delay the entrance of the king into the fray in any serious way. Since we won't be satisfied with a few comic defeat of the king why not have him disappear just like TIM and let Miranda take care of another archmage in a few comics? Well, for one thing it doesn't make logical sense for him to not take the matter in hand himself. However, I suspect Mookie will drum up some lame excuse like now that TIM has the treasure it demands the king's immediate attention and of course he can leave the last archmage to handle matters.
On the other hand, I can see a more exciting possibility. There are two opponents for Miranda and one potential ally. If she's able to free Celesto to help.