The promise of Dungeons and Dragons -- in all its editions -- is that two characters at the same character level will be comparable in power. This is the essence of game balance, and it satisfies us because it is fair.
The elegant solution to multiclassing in 3E is that when you advance a character level, you can take any available class level. ("Available" here means that you have to take level 1 in a class before you take level 2. You can't take cleric 5 before you take cleric 4.)
And since the game promises balance among characters of different classes, it also promises balance among characters of different multiclasses.
Now, let's step back for some caveats. In actual play, not all characters at the same character level are balanced so as to be equal in power:
1) Players are free to make suboptimal choices. A fighter using a dagger is not as powerful as a fighter using a greatsword. A sorcerer who selects Floating Disk and Disguise Self is not as powerful one who chooses Sleep and Shocking Grasp.
2) Not all classes are equal. Although this point is debatable -- and has been debated to death and back -- even if you make the most optimal choices, the high-level cleric is generally acknowledged to be more powerful than the high-level fighter, for example.
3) Not all levels are equal within a class. For example, a fighter 5 gains a hit die, skill ranks, and +1 BAB. A fighter 6 gains all that plus a feat and +1 on all saves. Moreover, all classes gain an extra boost to saves at level 1. And at level 1, one's skill ranks are quadrupled, and hit dice are maximized -- so if you want to be a skill monkey, the game pushes you to take a level of rogue or ranger or bard at first level.
4) Many multiclass combinations are clearly unbalanced. A cleric 5 / wizard 5 is not as powerful as a cleric 10 or a wizard 10. The mystic theurge, the arcane trickster, and the eldritch knight are all attempts to fix these problems -- for divinist/arcanists, rogue/arcanists, and warrior/arcanists, respectively. And some multiclass combos, especially using splat books, but also in a few cases for core classes, are more powerful. For example, in stacking save bonuses.
But that does not mean game balance is a lie. Rather, it just means that the game has room for improvement. That's what I aim to offer in this series.
- Make characters of equal class level more equal in power.
- Decrease granularity for all classes and levels.
- Revise multiclassing so that combining levels from different classes does not result in severely underpowered or overpowered characters.
This is part one of an ongoing series on How I Would Fix D&D 3.5.