Homebrew Archlich Species Details

Archliches appeared almost indistinguishable from normal liches. They had skeletal appearances and blank eye sockets containing only points of light, and their bodies showed no signs of life. They did not eat, sleep, or breath unless they wished to. Unlike common liches, their bodies and minds did not continue to deteriorate with time. As such, they had a virtual eternity to hone their skills, and would inevitably become very powerful.
The unique circumstances surrounding an archlich's creation meant that they had several unique powers. For one, upon the moment of their creation, an archlich was able to permanently affix up to nine spells in their memory, allowing them to cast these without the need for normal preparation or memorization. Most opted for a few offensive spells alongside fly and teleport. They could also walk on water and see perfectly clearly even in complete darkness.

Like other powerful forms of undead 0an archlich had unnatural powers owing to its state. For example, they could put mortals in a paralyzed state of hibernation with a touch, making them seem dead to others. An archlich was capable of sustaining tremendous physical damage, and was immune to disease, poison,  fatigue and other things that affected only the living. Owing to the unique methods by which an archlich achieved undeath, they were additionally immune to all mind-affecting charms or most shape-altering magics, and any mundane injuries. Despite all these undead "gifts", an archlich (like a lich) counted its vast intellect, its supreme mastery of wizardry and limitless time to research and plan, as its greatest resources. 

Archlich Traits

A lich which has reached the pinnacle of magical might.

Damage Immunities

necrotic, poison; bludgeoning, piercing, and slashing from nonmagical attacks

Condition Immunities

Immune to being charmed, exhausted, frightened, paralysed, and poison

Darkvision

Ability to see in the dark with up to 60ft

Damage Resistances

Resistant to cold, lightning