Immortality is the ability to escape death in some form, often through supernatural means. The tier of immortality achieved defines the limits of one's immortality.
Tiers
Tier 1
Tier 1 immortality is considered the highest form of immortality. Tier 1 immortals have no beginning and no end, and cannot be destroyed.
Tier 2
Tier 2 immortality grants immunity to aging and disease. However, Tier 2 immortal creatures may still be destroyed by physical or spiritual means.
Tier 3
Tier 3 immortality allows a creature to escape death temporarily.