I didn't have any problem soloing it as a Black Mage. The problem is being there when it starts, because if it's not engaged immediately, it will generally fail within a minute. I remember I twice ported into Bronze Lake and saw that it had just started (like 14:40-14:50 on the clock), and by the time I Chocobo-ed over there it was over due to the Kobolds killing the NPCs.