When I get to the point where I have master learning and want to start racking up experience by killing monsters, the first thing I always do is spawn all the energy drakes in north Kriegspire and then take them out (with a teacher and instructor in my party). You can kill them all with Armageddon, though that may take a few days, or with Dragon Breath - generally a lot quicker though a little more risky. I've taken them down with Meteor shower, but you really need to be careful with that.
It is an immense amount of experience and will get you a bunch of levels, plus a ton of loot. I usually find that that's the turning point in my games.
Problem: with a solo character, you're going to have to hit that well 50 times to spawn all of them and you can only use it once a day. 8 of them spawn every time you hit the well, and there are 400 of them. With a full party, you only need to hit it for 13 days. I have, on other solo games, considered resurrecting the other party members long enough to do that, but in the end always just decided to bite the bullet and go through the 50 days.