[Radek]

There are two general rules for dualling:
- Dual immediately after gaining a special (and essential) advantage in the old class.
- Keep in mind that your new class has to gain a level higher than the level of your old class to reactivate the old class abilities. Example:
Kensai/MAGE. Dual at level 9 in SoA or at level 13 in ToB. At level 9, you gain new Kai attack and an attack bonus. At level 12 you gain the same. At level 13 you gain another fighter bonus. Now, level 12 or 13 are too late for SoA because the mage would have to reach level 13 or 14 to become a kensai/MAGE - it's too late for SoA. On the other hand, level 13 is okay for ToB. Mages or clerics will dual after gaining the wanted spell level. Other classes can dual immediately - if you find the advantages ahead unessential. And so on.