A lich has essentially converted their existance from life to unlife. It
is
as sustained as normal life. The cost is a rather barbaric and evil ritual
to get there in the first place, a fundamental shift of their existance
to
something that is not natural, and a permanent lack of the "spark" that
defines the humans. Clerical powers are lost, as is the appreciation for
the natural beauty of living things. Given all this and ignoring any
nastiness associated with the ritual, if a lich can cope with it all without
going insane, he may not be "evil" in the traditional sense.
A lich is the only (or most common) voluntary member of the unlife.
Vampires are an involunatary member of the unlife. A vampire kills his
victim
in a particular way, which leaves him drained and vulnerable. His victim
becomes
a wight enters him. At the time of the conversion, the victim makes a save
vs.
death magic--wisdom mods but no other assistance. A successful saving throw
means that the victim may in time become a vampire, when his will reasserts
itself over the influence of the unlife.
If he fails, then his chi (or whatever) is lost forever, and he will always
be a wight.
Vampires and wights are not as connected to the unlife as liches, and must
feast on life to sustain their own unlife. Failure to do so renders them
weak and vulnerable--to the point of catatonia. However, unlife never leaves
them, and they may be catatonic but unlifed for eternity.
As they are no longer infused with life, they can not be killed. They can
be destroyed, physically, but not by wounding them in combat. Means differ,
and some of the unlife are invulerable to certain attacks, but fire and
magical dismemberment are favorites.
One final note, unlife only affects humans. It is actually a corruption
of
their so-called spark. Elves, Dwarves and the dark folk are all immune
to its
power. Question: is lycantropy a corruption of humans ability to adapt?
Just
asking?