Further context, assuming the ruleset governing the OG Baldurs Gate games was true to the tabletop (I know they sort of kludged AD&D and aspects of 3e together). As the above said, a dual classed human “retires” their original class, and then begins to advance in their new class, essentially starting over from level 1, with only the hit dice and HP of their original class rolled over (you cannot access any of the class abilities you learned while advancing your original class). However, once your new class level is superior to your original class level, you can now access both skill sets.
It’s a very strange system, and I am curious what the fluff reasons surrounding it are, if anyone has any insight into that edition.
I remember it being especially bizarre because it basically means going through a large portion of the game with a more or less useless character soaking up xp, after which you either have a slightly less useless underlevelled character or one that’s brokenly OP depending on how you planned out the combo. And if you dual class too late you just never get to that point and it’s all drawback no benefit.
In AD&D, you still had access to the abilities of your retired classes, but if you used them you had experience penalties (if you use them in an encounter, you gain no experience for that encounter and your experience for the entire adventure is halved) . The reason was that you were supposed to be learning to do things a new way, and if you fell back to the old way, you weren’t pushing yourself anymore. From the AD&D PHB, under “Dual-Class Benefits and Restrictions”:
This is not to imply that a dual-class human forgets every-thing he knew before; he still has, at his fingertips, all the know-ledge, abilities, and proficiencies of his old class. But if he uses any of his previous class’s abilities during an encounter, he earns no experience for that encounter and only half experi-ence for the adventure.
The paragraph goes on to explain what’s restricted (everything but HD and hit points), then ends with:
(The character is trying to learn new ways to do things; by slipping back to his old meth-ods, he has set back his learning in his new character class.)
