Ceara

Legendary Resistance (3/Day). If the lich fails a saving throw, it can choose to succeed instead.

Rejuvenation. If it has a phylactery, a destroyed lich gains a new body in 1d10 days, regaining all its hit points and becoming active again. The new body appears within 5 feet of the phylactery.

Spellcasting. The lich is an 20th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 22, +15 to hit with spell attacks). The lich has the following wizard spells prepared:

Cantrips (at will): mage hand, prestidigitation, ray of frost

1st level (5 slots): detect magic, magic missile, shield, thunderwave

2nd level (4 slots): acid arrow, detect thoughts, invisibility, mirror image

3rd level (3 slots): animate dead, counterspell, dispel magic, fireball

4th level (3 slots): blight, dimension door, polymorph

5th level (3 slots): cloudkill, scrying, animate objects, hold monster

6th level (2 slot): investiture of wind, globe of invulnerability

7th level (2 slot): finger of death, reverse gravity

8th level (1 slot): dominate monster, power word stun

9th level (1 slot): power word kill

Arcane Scientist. As a ritual, the lich may spend 3 hours to cast time stop and true polymorph on a creature that has died in its dread realm. This does not take up any spell slots. The Time Stop causes the true polymorph spell's casting time to only take 3 rounds from the targets point of view. Saves against this ritual are made at disadvantage. The modifications made with this spell are drawn from a list of mutations.

Domain's Resurrection.  When a creature, that is inside of the lich's dread realm, reaches 0 hit points and 3 failed Death Saving Throws, it is given the option to be resurrected at the next rising of the sun. It is revived with a modification and 1 level of exhaustion that cannot be magically removed. This Exhaustion level is removed after a 6 hour rest or a long rest. When it fails its last saving throw, there is a 10 minute time period that it may be resurrected by its companions or another creature with no modification or level of exhaustion. At the end of this 10 minute time period, it will have a 10% chance to have a brief conversation with the lich before awaking at the next sunrise.

Turn Resistance. The lich has advantage on saving throws against any effect that turns undead.

Destroyed Pylon Buffs. 
If one pylon is destroyed the lich may use the attack Lich Slap as a Bonus action.
If two pylons are destroyed, the lich may concentrate on a maximum of 2 spells. If the Lich must make a concentration check, it makes one for each spell. The DC for the Concentration Check becomes 13 or half of the damage taken, whichever is higher.
If three pylons are destroyed, the lich gains he effects of a Ring of Spell Turning which is: "You have advantage on saving throws against any spell that targets only you (not in an area of effect). In addition, if you roll a 20 for the save and the spell is 7th level or lower, the spell has no effect on you and instead targets the caster, using the slot level, spell save DC, attack bonus, and spellcasting ability of the caster."
If four pylons are destroyed, the lich becomes mythic, gaining the following: 5 Mythic actions, it may use its Mythic Actions to perform the Mythic Actions listed in the Mythic Actions Description, and it gains Temporary Hit Points equal to its Maximum Hit Points.

Multi-attack. The Lich may cast a non-concentration spell of 7th level or lower and then make an attack with Paralyzing Touch with a range of 10 ft.

Paralyzing Touch. Melee Spell Attack: +14 to hit, reach 5 ft., one creature. Hit: 10 (3d6) cold damage. The target must succeed on a DC 18 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Lich Slap. Melee Attack: +13 to hit, reach 5 ft., one creature. Hit: 5 necrotic damage.  The target takes the damage and has its Maximum Hit Points reduced by the amount of damage taken. This reduction may only be removed with a Greater Restoration spell cast at 7th level or 1 long rest for every 10 points of reduction. Any creature that has its Maximum Hit Points reduced to 0 is dead unless a resurrection, reincarnate, wish, or divine intervention is used to revive it. The Domain's Resurrection ability may not affect this creature for 1 year. If this attack deals damage to a target with Temporary Hit Points, the Hit Point Maximum is still reduced.

The lich can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The lich regains spent legendary actions at the start of its turn.

Cantrip. The lich casts a cantrip.

Paralyzing Touch (Costs 2 Actions). The lich uses its Paralyzing Touch.

Frightening Gaze (Costs 2 Actions). The lich fixes its gaze on one creature it can see within 10 feet of it. The target must succeed on a DC 18 Wisdom saving throw against this magic or become frightened for 1 minute. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to the lich's gaze for the next 24 hours.

Disrupt Life (Costs 3 Actions). Each non-undead creature within 20 feet of the lich must make a DC 18 Constitution saving throw against this magic, taking 21 (6d6) necrotic damage on a failed save, or half as much damage on a successful one.

If the Lich is Mythic, it can take 6 legendary actions instead of 3, choosing from the legendary actions or the Mythic actions below. Only one action can be used at a time and only at the end of another creature's turn. The lich regains spent legendary actions at the start of its turn.

Spell (Costs 2 Actions). The lich casts a spell with a casting time of one action or less.

Lich Slap (Costs 1 Action). The lich uses its Lich Slap.