Despite the bookkeeping hassle and the strained in-game explanations, level drain has one thing in its favor: inciting terror amongst players. This is a good thing, as the undead ought to incite terror, but it has its drawbacks: namely the fact that high level characters are far less vulnerable than low level characters. Some may assert that this is justifiable for the same reason that high level characters have more hit points, and thus are more difficult to kill, but I would respond that true terror ought to transcend the relative safety of experience. In fact, that's one of its most unsettling characteristics. This is why I have decided that in my own games, energy drain refers not to levels, but to how many six-sided dice you roll to determine your reduction in strength (which, at least in the version of Dungeons & Dragons I play, is independent of character level). Most undead will cause 1d6 points of strength to be drained. More powerful undead, such as vampires, will drain 2d6 points of strength. Zero strength equals death (and probably eventual undeath). If one survives such an attack, strength is restored at the rate of 1 point per week of rest. The usual spells (i.e. restoration and wish) will fully restore lost strength. As with the traditional energy drain, there is no saving throw to avoid its effects.