In many ways, level drain is one of the most devastating attacks in D&D and has been from the very beginning. Fighting an Orc and dying can be a chance to try out a new character, being raised from the dead has few consequences in recent editions (if you pay enough), but level drain is still terrifying. A bad saving throw or two can undo months of adventuring.
I’m writing about level drain in response to brcarl’s suggestion pot question  from last year.
I’d like an article discussing level drain: pros, cons, how to handle it so it’s effective (scary!) but not debilitating/frustrating, etc.
FYI, the DM in one of my 3.5e D&D tabletop games is running an on-going campaign where level-drain seems to always come up as the focal plot device, and it’s starting to tick off some of the players (me included). The reason is that we have no cleric in the party, and the game world (home-brew version of Ravenloft) doesn’t provide many sufficiently-powered clerics and/or magic items to help us rid ourselves of the accursed affliction. What’s a poor, repressed PC to do?
Level Drain in Novels
Let’s begin by looking at what level drain is meant to model. It’s a little strange at first thought– why does getting bitten (or punched) by a vampire involve forgetting spells? And why do the effects of level drain last so long? A character can be healed from death’s door to almost full health with one quick spell or only a few days rest. Why can’t you overcome level drain (in older editions of D&D), and why isn’t it just part of healing (in new editions)?
I suspect an early source of inspiration for level drain was Ursula LeGuin’s A Wizard of Earthsea, which was a popular book released in 1968– shortly before D&D came together. In the book, Ged accidentally summons a gebbeth [a shadowy wraith like creature], whose touch paralyzes Ged and weakens him. When he awakens from a coma months after the attack, his spell making is halting and has to return to classes he’d previously breezed past, where he struggles for months. This is very similar to the effect of level drain in D&D; hard won knowledge (like spells, feats, and attack bonuses) are stripped away, and don’t return easily.
Other novels have similar lingering results from undead; chills that wrack the victim to the bone, the weakness of blood loss from a vampire’s feeding, and the stupor inflicted by the poisoned tails of the Dark. In books, wracking the one hero for months can be fascinating, but it doesn’t always translate well into group play.
Level Drain in Play
Throughout the editions of D&D prior to 4e, level drain was a constant feature of powerful undead. As D&D evolved through its editions, level drain maintained similar core features. In the beginning, you immediately subtracted experience from the character sheet, but this evolved into adding “negative levels” to make it quicker to approximate losing levels. This was probably tied to the increased complexity of leveling characters, which made it harder to roll them back simply.
Level drain is just about as difficult to cure as death even in 3.5. (In older editions, I remember it being even harder to cure– or at least, the cure was a lot less commonly available.)
Level drain remains an effective threat throughout a character’s life. It requires a costly, unusual spell to counter its effects– and the threat of losing months of experience does a good job of scaring the player. In low magic or restricted cure campaigns, level drain can be a terrifying effect– one that questions the character’s willingness to risk the loss of so much effectiveness in this one fight.
Level drain models one aspect of fights that general D&D doesn’t normally address: Pyrrhic victories. You can win fights against level draining monsters, and still come out well behind where you started. (The death or petrification of allies is a similar but more extreme form of the same thing.)
Mitigating Level Drain
In high magic campaigns, there’s not much need to mitigate level drain in later editions of D&D. Much like death, purchasing the proper scrolls in advance lets characters deal with the debilitating effects of level drain immediately, greatly reducing its impact. (It becomes a slightly less disrupting alternative to character death.)
In low magic campaigns, level drain can be messy and drastically influence the game. Much like the spiral of death (characters dying and being raised results in coming back at lower level, making them less able to handle the next fight, making it likely that they’ll die again and be even further behind the expected power of the adventure), level drain is cumulative and deadly. Unlucky level drains can swing battles; the wizard loses the spell that would have blasted through the battle, or the fighter begins missing by one or two instead of hitting by the same margin.
Many of the solutions that take some of the sting out of death work equally well for level drain. Here are some ways of handling level drain that might feel less punitive.
Permanent Negative Levels As currently written, if you don’t get restoration cast on your character within 24 hours and fail the saving throw, you eliminate the negative level but roll the character back one level. (So the temporary negative level is replaced by you actually doing the work of rolling your character back.) With this solution, your character is still weakened like normal, but you save the work of rolling your character back.
Negative Levels Vanish on Level Gain Borrowing from Andy Collin’s The High Cost of Dying  article, energy drained levels could be treated similarly to death inflicted special negative levels. When the character advances in level normally, they also get to remove one negative level. This means negative levels stick around for a while, but they don’t permanently cripple the character.
Chills and Other Effects Depending on the way you want level draining to look, as the GM, you might want to consider using a different mechanic. Ability Drain and Damage are common among the undead, and disease like effects might better match what you imagine the touch of the undead inflicting. Similarly, the Bestow Curse options make a great shopping list of substitutions for level drain. Other spells (particularly from the necromancy school) can make great alternatives.
Level Drain and You
As a player, I know that level drain is one of the effects that I hate more than anything. It can be particularly annoying, in that it widens the level gap between the characters in a group, and makes weak characters even less useful and more likely to die. It sucks to be the fighter keeping the creatures away from the wizard– and losing levels, not just hit points, while doing your job.
As a GM, I have seen level drain be a great motivator. The players’ fear can make for a battle that feels momentous even if the creature has no chance of winning. The chance of landing a blow or two during the battle makes it tense– that’s a lot of adventuring experience on the line!
How does level drain work in your games? Have any of you faced frequent level drain, as brcarl has? Does it feel like cheating, and do you resent a mechanic that undoes months of play in a couple of hits? Are you old school and laugh at allowing fortitude saves to avoid the effect? Does level drain have a positive role in the game, or is it just an unthinking hangover from an earlier era?