Domain Expansion: Lich Phylactery

You create a demiplane centered on yourself. This demiplane is the ultimate spell in terms of both defensive and offensive capabilities, and mimics the power of a Lich's Phylactery. To the outside world this area looks like a cube of greyish black smoke (this cube functions as a massive, cube-shaped Wall of Force). Every creature in the 150 foot cube's radius when this spell is first cast must make an Intelligence saving throw against your spell save DC. On a successful save the creature appears just outside of the spell range in an unoccupied space. On a failed save the creature is swallowed within the demiplane, trapping it inside for the entire duration. Any creatures outside or inside the cube cannot enter or exit it by any means, including teleportation magic. 

Terrafirma. The demiplane looks like however you like. You control the environment and you can choose whether or not to harm any creature in the demiplane. As an Action on your turn, you can change the environment/layout of the space within the 150 ft cube, as if casting the spell, Hallucinatory Terrain, in tandem with the spell, Major Image. These illusory landscapes and changes count as 'pseudo-real' within the domain.

When you first cast the spell, you can select any 5 'lair' or 'domain' effects from the list below, as part of the casting Action (if the spell is successful in capturing the enemy). The effects detailed below use the DC or spell attack bonus in the description, or your own spell save DC and spell attack bonus - whichever is higher. In addition, you can choose to roll the damage, or use the average listed in the description. On your turn; you can take a lair action to cause one of the following effects; 

• 3rd Level Spell. The caster casts any third level spell from any classes spell list.

• Infernal Illusions. The caster casts the major image spell four times, targeting different areas with it. The caster prefers to create images of intruders' loved ones being burned alive. The caster doesn't need to concentrate on the spells, which end on initiative count 20 of the next round. Each creature that can see these illusions must succeed on a DC 26 Wisdom saving throw or become frightened of the illusion for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

• Fog of Deception. The caster conjures a magical cloud that fills a 30-foot-radius sphere centered on a point it can see within 90 feet of itself. Each creature in that area must make a DC 24 Wisdom saving throw. On a failed save, a creature has the charmed condition until the end of its next turn. While it has the charmed condition, the creature must use its action to make a melee attack against a creature other than itself of the casters choice. If no creature is within its reach, the affected creature makes a ranged attack against a creature of the caster's choice, throwing its weapon if necessary. On a successful save, a creature is immune to the caster's Fog of Deception for the next 24 hours.

• Deadly Utterance. The caster's voice booms throughout the lair. His utterance causes one creature of his choice to be subjected to power word kill. The caster needn't see the creature, but he must be aware that the individual is in the lair.

• Grasp of the Dead. The caster causes skeletal arms to rise from an area on the ground in a 20-foot square that he can see. They last until the next initiative count 20. Each creature in that area when the arms appear must succeed on a DC 23 Strength saving throw or be restrained until the arms disappear or until caster releases them (no action required).
• Undead Servants. The caster causes up to six corpses within the lair to rise as skeletons, zombies, or ghouls. These undead obey his telepathic commands, which can reach anywhere in the lair.
• Darkness.  The caster casts the darkness spell four times, targeting different areas with the spell. Doesn't need to concentrate on the spells, which end on initiative count 20 of the next round.
• Illusory Duplicate.  The caster creates an illusory duplicate of himself, which appears in his space and lasts until initiative count 20 of the next round. On his turn, caster can move the illusory duplicate a distance equal to his walking speed (no action required). The first time a creature or an object interacts physically with caster (for example, by hitting him with an attack), there is a 50 percent chance that the illusory duplicate is affected, not caster, in which case the illusion disappears.
• Impale. The caster causes an iron spike—6 feet tall and 1 inch in diameter—to burst from the ground at a point he can see within 100 feet of him. Any creature in the space where the spike emerges must make a DC 24 Dexterity saving throw. On a failed save, the creature takes 27 (6d8) piercing damage and is restrained by being impaled on the spike. A creature can use an action to remove itself (or a creature it can reach) from the spike, ending the restrained condition.
• Mass Command. The caster casts the command spell on every creature of his choice in the lair. He needn't see each one, but he must be aware that an individual is in the lair to target that creature. He issues the same command to all the targets.
• Conjure Mirrors. Smooth surfaces within the lair become as reflective as a polished mirror. Until a different lair action is used, creatures within the lair have disadvantage on Dexterity (Stealth) checks made to hide.
• Green Slime. A green slime (see the Dungeon Master's Guide) appears on a spot on the ceiling that caster chooses within the lair. The slime disintegrates after 1 hour.
• Slippery Slime. The caster slimes a square area of ground it can see within the lair. The area can be up to 10 feet on a side. When the slime appears, each creature on it must succeed on a DC 21 Dexterity saving throw or fall prone and slide 10 feet in a random direction determined by a d8 roll. When a creature enters the area for the first time on a turn or ends its turn there, that creature must make the same save. The slime lasts for 1 hour or until it is burned away with fire. If the slime is set on fire, it burns away after 1 round. Any creature that starts its turn in the burning slime takes 22 (4d10) fire damage.
• Sticky Slime. The caster slimes a square area of ground it can see within the lair. The area can be up to 10 feet on a side. When the slime appears, each creature in that area must succeed on a DC 21 Strength saving throw or become restrained. When a creature enters the area for the first time on a turn or ends its turn there, that creature must make the same save. A restrained creature is stuck as long as it remains in the slimy area or until it breaks free. The restrained creature, or another creature that can reach it, can use its action to try to break free and must succeed on a DC 21 Strength check. The slime lasts for 1 hour or until it is burned away with fire. If the slime is set on fire, it burns away after 1 round. Any creature that starts its turn in the burning slime takes 22 (4d10) fire damage.
• Magic Recovery. The caster rolls a d12 and regains a spell slot of that level or lower. If it has no spent spell slots of that level or lower, nothing happens.
• Nether-Tether. The caster targets one creature it can see within 30 feet of it. A crackling cord of negative energy tethers the caster to the target. Whenever the caster takes damage, the target must make a DC 18 Constitution saving throw. On a failed save, the caster takes half the damage (rounded down), and the target takes the remaining damage. This tether lasts until initiative count 20 on the next round or until the caster or the target is no longer in the casters lair.
• Spirit Call. The caster calls forth the spirits of creatures that died in its lair. These apparitions materialize and attack one creature that the caster can see within 60 feet of it. The target must succeed on a DC 18 Constitution saving throw, taking 52 (15d6) necrotic damage on a failed save, or half as much damage on a success. The apparitions then disappear.
• Chill Blast. The caster causes a blast of cold to burst from the ground at a point he can see within 120 feet of him. The cold fills a cube, 10 feet on each side, centered on that point. Each creature in that area must succeed on a DC 21 Constitution saving throw or take 28 (8d6) cold damage.
• Hateful Restraints. The caster targets one creature he can see within 60 feet of him. The target must succeed on a DC 21 Wisdom saving throw or become restrained for 1 minute. The target can end the effect on itself if it deals any damage to one or more of its allies.
• Eye-Blight. The caster taps into the eyesight of creatures in its lair and alters their perception. Each creature of casters choice in the lair must make a DC 22 Wisdom saving throw. On a failure, the affected creature perceives objects and creatures a short distance from their actual locations, imposing disadvantage on the creature's attack rolls against those targets. An affected creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to this lair action for the next 24 hours.
• Eyebeam. An eye opens on a solid surface within 60 feet of the caster. One random eye ray of caster's shoots from that eye at a target of caster's choice that it can see. The eye then closes and disappears.
• Wave of Madness. The caster creates a wave of madness. Each creature it can see within its lair must succeed on a DC 22 Wisdom saving throw or be charmed for 1 minute. While charmed in this way, a creature must use its action at the start of its turn before moving to make a melee attack against another creature of caster's choice within reach. If there are no creatures within reach, the charmed creature can act normally for that turn. A charmed creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
• Heart-Sight. The caster learns about any creature touching any  environment that you have created in your domain. Each creature must make a DC 21 Intelligence saving throw. On a failed save, the caster gains knowledge of a creature's name, race, where they consider home, and what brought them to this world.
• Summon Creature. The caster casts a summoning spell of its choice. It lasts until the caster uses this lair action again or until the caster dies.
• True Resurrection. While inside your own domain, you are under the permanent effects of True Ressurection. If you die, this spell triggers and you come back to life on the start of  your next turn.
  

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  This spell was created by the magi of wonder and whimsy; Cameron the Clairvoyant. He loved to create, and was inspired by many things around him - people, places, things, concepts, nature, anime, pop culture - and loved to craft superior unique things for the Dungeons and Dragons community. Check out his homebrew creations in every category on D&DBeyond, and feel free to incorporate them into your homebrew campaigns. Cameron the Clairvoyant is a former player-character that reached level 20 and now functions as a NPC Archwizard, and has created numerous impactful magic items, weapons, subclasses, monsters, creatures, feats and spells. Seek him out in your next quest! He loves to take requests and interact with parties of player-adventurers.