Do not change classes, period. Plan a basic/elite mixed party (Fig-Mon-Ran-Bar-Pri-Mag would be a good build, using Knock Knock) and stick with them. The game is designed to balance out previous installments where you could make uber characters by switching classes. When you change here your experience and total level stay the same, so for example a level 20 priest changing to a bishop will essentially need the same amount of experience needed to go from 20-21 to become a level 2 bishop.
- John
http://www.tk421.net/wizardry/