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Energy Drain
Necromancy
Level: Clr 9, Sor/Wiz 9
Saving Throw: Fortitude partial; see text for enervation
This spell functions like enervation, except that the creature struck gains 2d4 negative levels, and the negative levels last longer.
There is no saving throw to avoid gaining the negative levels, but 24 hours after gaining them, the subject must make a Fortitude saving throw (DC = energy drain spell’s save DC) for each negative level. If the save succeeds, that negative level is removed. If it fails, the negative level also goes away, but one of the subject’s character levels is permanently drained.
An undead creature struck by the ray gains 2d4x5 temporary hit points for 1 hour.
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Restoration
Conjuration (Healing)
Level: Clr 4, Pal 4
Components: V, S, M
This spell functions like lesser restoration, except that it also dispels negative levels and restores one experience level to a creature who has had a level drained. The drained level is restored only if the time since the creature lost the level is equal to or less than one day per caster level. A character who has a level restored by restoration has exactly the minimum number of experience points necessary to restore him or her to his or her previous level.
Restoration cures all temporary ability damage, and it restores all points permanently drained from a single ability score (your choice if more than one is drained). It also eliminates any fatigue or exhaustion suffered by the target.
Restoration does not restore levels or Constitution points lost due to death.
Material Component: Diamond dust worth 100 gp that is sprinkled over the target.
That is how energy drain is balanced in the DnD world. We need a priest-only spell like restoration, so when you get drained a level, you need to rush to one to get them restored before the time wears out. Maybe there is some way to put a material component cost on it as well. With a spell like restoration, energy drain can be made wicked.