[roller1234]

It goes like this:

BG1 - multiclass overpowered
BG2 SoA - dualclass overpowered
BG2 ToB - multiclass overpowered

Reasons: Due to an uneven exp scale, early on you can have a whole additional class for a small cost of one level, that is lvl6/6 or lvl7. Later on, having a lvl9 dualed to something costs basically nothing, but grants huge bonuses, the way they are distributed( just about everything is pre lvl9). However even more later, other, more powerful, stats are starting to cap, like spell power or thac0. This is(very late game, lvl20/lvl20) where multiclassed chars are beginning to truly dominate the playing field. Plus they get HLAs of both classes too. Scary. Jaheira is a truly sick character later on.