The spell dimension door is a very powerful spell. Not only are its effects
enormous, but the results of miscasting this very erratic spell. It rips a
hole into the fabric of time and space, creating a portal. This rift in
reality allows travel from one point, the casting point, to various places,
mostly out through other such rifts. This spell takes a great amount of
concentration and effort, and can go very wrong. Due to the nature of space
and time and the upsetting of balances this spell can cause, the caster can
sometimes be inflicted, overpowering his casting ability, making him useless
for a short time. Also, opening rifts may allow things through them into this
world, things that should not be here for many good reasons. . .