Is there any single word which encompasses the concept or active avoidance of death, specifically through the use of necromancy, reanimation, or other forms of immortality?
An example sentence would be,
"Some recurring thematic elements in H. P. Lovecraft's work includes dark familial legacy, other-worldly beings, degeneration, self-destruction, mind control, as well as [the avoidance of death] / [the use of Necromancy, reanimation, and immortality]."
I think you might mean the "negation of death" rather than the "avoidance of death".
As in Kyle's answer, the avoidance of death is "self preservation" or "survival" as in Chromane's answer.
"Amortal" might also cover the avoidance of death. Collins English Dictionary has a definition:
Pursuing a lifestyle that defies the process of ageing
Urban Dictionary goes further:
Unable to die from disease or age. Immortal if no physical ailment befalls you
The words for the negation of the "effects" of death tend to be specific to particular folklore. Vampire are "undead", zombies are "living dead" or walking dead".
There is also "reanimated". Collins give the meaning of "to bring back to life".
Well, self-preservation covers "the avoidance of death", but I'm not familiar with too many words that relate to necromancy. You could derive a word from Lazarus and people would most likely know what you are talking about. Lazarus is used a couple of times in science to describe things that 'come back from the dead', for example, lazarus taxa.
Immortality, surely?
The quality or condition of being immortal; exemption from death or annihilation; endless life or existence; eternity; perpetuity (ODO).
Suggestions:
In a metaphysical sense: "transcendence"
During a fight: "flee" or "escape"
A more religious term from the Bible: "transmuted" or "raised"
In that necromancy = sorcery, that's what it is and so that's what it could be called. Pretty simple, really. And given that it's impossible to cheat Death shows you how effective it is. Another word I often use to describe that sort of behavior, is superstition:
...religious belief based on fear or ignorance and considered incompatible with truth or reason," literally "a standing over," noun of action from past participle stem of superstare "stand on or over; survive,"
