A
ubiquitous and woefully underused
spell, present in all of the
Final Fantasy games released in America. Drain is available to
black mages in
FFII, through the
esper Ifrit in
FFIII, and through the
materia "HP Absorb" in
FFVII. It can probably be found lying around in
FFVIII, but I haven't played it that far yet.
The effect of drain, is, of course, to take hit points away from the enemy and transfer them to you. Note that the conduit reverses if you attempt to use this spell on the undead. You wind up taking some of their negative hit points, which has the result of doing you damage. The drain spell is actually rather weak, and ceases to be useful shortly after you learn it in any case.
A related spell, known as "osmose" in FFIII and available through the "MP Absorb" materia in FFVII, takes magic points from the enemy instead, and could be considered a "brain drain".