Fly—even when I don’t really need to get somewhere high up, the speed boost alone often makes it worth it.
Wizard Eye—it’s an excellent to keep track of dead bodies and finding loose items
Invisbility—A good way to get through smaller dungeons quickly, though of course it depends on the dungeon.
Acid Burst, Meteor Shower—probably my most commonly used offensive spells, Acid Burst does good damage and Meteor Shower along with fly is good for hordes of weak, non-ranged foes. Mass Distortion is also nice when I have it.
Pain Reflection—the only Dark spell I use regularly, but it makes it sooo much easier to bring down foes I normally wouldn’t stand a chance against…
Town Portal/Lloyd’s Beacon—this is mostly for speed and saving frustration—I don’t have to check stables or boats, and I don’t have to waste travel time.
Miscellaneous healing spells—of course this is so general and obvious I hesitate to mention it.
Berserk—this was mostly in MMIX. Running through the Path of Darkness or whatever to get my Writ of Fate at low-level would have been impossible without this and Turn Undead. It’s also loads of fun to cast on the Winged Terrors in the passage between Thronhiem and Thojorgard.
Preservation and Regeneration—usually in concert, and with Pain Reflection if possible.
On the other hand, I almost never use: Telepathy (waste of time and spell points), Charm (why Charm it if I can kill it? And if I can’t I’ll be too busy retreating to cast the spell anyway), Stun, Divine Intervention (as mentioned before: the age penalty), Fate, most of the lower-level offensive Earth spells and most of the offensive Light and Dark spells (I think this is at least in part because it’s unavailable for so long in MMVII—by the time I can get it, my other spell skills have progressed enough that I use them instead).
But what about you? What spells do yo rely on and what spells do you never touch?
