Thank you, Bakasi.
I had envisioned a world in which every spell cast cost one part of one's essence. The essence was what powered the spell. Use it all up and you die. For a short period after you die, a powerful wizard can reincarnate you by reinfusing you with essence. One spell typically wouldn't kill the musician, unless they are already running very low on essence.
I haven't fleshed out this world enough to know whether they are giving you an "essence transplant" from themselves or whether they could, somehow, gather essence from the environment. Of course, things could turn really dark really fast if an essence transfusion is like a device which featured a brief but pivotal role in the TV series Babylon 5. The original creators of the device intended it to be used for both capital punishment and healing. Basically, the device transfers the infirmities of the ill person to the criminal.
Since I prefer the demon dragons to be the major threat in my story, I'll assume that a wizard of great skill and power can harvest essence from the atmosphere, but only at some great cost to himself or the town.
Joy,
Lynn
