Exiles at the Well of Souls
by Jack L. Chalker
The Well World, a construct of the now-defunct Markovians, acts both as the controller of and the gateway to 1560 worlds created by that ancient race of beings. From far away, Obie, the self–aware computer, accidentally causes a whole world to be transported next to the Well World, and the changed circumstances set off a war of good vs. evil. This is the second book set in the Well World universe.