For a multi, at the first level up, AFTER you have reached 3.000.000 TOTAL XPs.
(So, if you have a fighter/thief, when you reach 1.500.000 in each class, you start gaining the abilities)
For a dual, you have to spend some more points, the total DOESN'T matter, you have to reach 3.000.000 points in the ACTIVE class....
