What happens when 1st level character fails a save on an energy drain?
Does he become "0-level" or does he die?
Dead, Dead, Dead and likely undead depending on the source of the negative energy level.
But he can fight on for 24 hours before he has to make the check?
Not so much, unless he has some means of ignoring the negative level for that time frame. You eat that last negative level you drop on the spot, temporary or no.
If negative levels equal your character's level, you die... instantly.
Energy Drained
The character gains one or more negative levels, which might become permanent. If the subject has at least as many negative levels as Hit Dice, he dies. See Energy Drain and Negative Levels for more information.
Energy Drain and Negative LevelsSome spells and a number of undead creatures have the ability to drain away life and energy; this dreadful attack results in “negative levels.” These cause a character to take a number of penalties.
For each negative level a creature has, it takes a cumulative –1 penalty on all ability checks, attack rolls, combat maneuver checks, Combat Maneuver Defense, saving throws, and skill checks. In addition, the creature reduces its current and total hit points by 5 for each negative level it possesses. The creature is also treated as one level lower for the purpose of level-dependent variables (such as spellcasting) for each negative level possessed. Spellcasters do not lose any prepared spells or slots as a result of negative levels. If a creature's negative levels equal or exceed its total Hit Dice, it dies.
A creature with temporary negative levels receives a new saving throw to remove the negative level each day. The DC of this save is the same as the effect that caused the negative levels.
Some abilities and spells (such as raise dead) bestow permanent level drain on a creature. These are treated just like temporary negative levels, but they do not allow a new save each day to remove them. Level drain can be removed through spells like restoration. Permanent negative levels remain after a dead creature is restored to life.
so yeah, a single wight can make for a very scary zombie apocalypse in a rural township or two.
THAT was EXACTLY my question.... I had thought I had gotten something wrong, because Wights were seemingly to powerful for CR3....
Thanks for the answer, all.
Meh, he's +4 to hit on a regular attack with an AC of 15 (both are rather low for level 4). He has meh hit points with not much to offer in save throws.
What really does it for the wright is the intelligence and good stealth modifier (+8 racial really does him a good turn).
Also it depends on what your 'average' village is. I have a thread on just that topic if you like.