Immortality

Immortality is when someone achieves eternal life and can never die. Two ways of achieving immortality have been shown:

Cornelius Sigan's jewel
This jewel allowed the powerful sorcerer Cornelius Sigan to achieve immortality. He presumably cast a spell to transfer his soul inside the jewel and enchanted it to contain his soul.

Cup of Life
When a persons blood is put on the Cup of Life, the person can become immortal. They cannot be harmed ordinary weapons and possibly magic as well, except a sword forged by a dragons breath like Excalibur.