Ruling Caerleon and fighting in the arena aren't so different for Cai. The King uses his wit and intellect to avoid work (and fighting) and uses combat as as last resort. He is well prepared for the horrors of the battlefield in either case. Exablast is more than powerful enough to torch anyone who gets in Cai's way, and that isn't all. Cai has healing and several other elements to draw on. A Warlock with mastery over several elements is scary enough, but a Warlock with access to flight is enough to send most of the DL running in terror!