Geistmage

Your soul and your body are entangled by an etheric essence known has geist that provides you with a sort of transplanar essence. Geist feed your mind, your blood end protect you from different hazards: age, necrotic damege and poison

Geist immunities

1st-level Geistmage feature

Your geist essence fully protect you from necrotic damage and poison

Geist armour

Your body in enveloped by the etheric geist and you add your CHA bonus to your AC. 

Long life

Starting at 6th level,   you age at a slower rate. For every 10 years that pass, your body ages only 1 year, and you are immune to being magically aged.

Etherealness

Starting at 14th level, you learn the Etherealness spell, but it doesn’t count against your number of sorcerer spells known

Unearthly Recovery

At 18th level, you gain the ability to overcome grievous injuries. As a bonus action when you have fewer than half of your hit points remaining, you can regain a number of hit points equal to half your hit point maximum.

Once you use this feature, you can’t use it again until you finish a long rest.