*Having two spells with identical effects, but with differing parameters, can be helpful: the short-duration levitation spell one uses to circumnavigate typical dungeon obstacles may need a longer-duration counterpart in the Mantella Crux, for example.
*Spells based entirely on the Destruction skill can easily be practiced for free, thereby resulting in a rapid rise in that skill. This can alter the casting cost of such a spell greatly in short amount of time.
**A very high-chance ''continual damage'' spell with a long duration will often be more effective than a lower-chance spell with a higher per-round damage potential.
**Some spell effects; notably ''paralysis'' and ''soul trap'', are all-or-nothing. Chance for these spells should have precedence over duration in most cases.