Domain Expansion

You create a demiplane centered on yourself. This demiplane is both defensive and offensive. to the outside world this area looks like a greyish black smoke. every creature in the radius when this spell is first cast must make a charisma 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 stays within the demiplane. A creature from the outside can enter. If a creature is on the inside and find the edge of the demiplane they can leave it.

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 you can choose to harm a creature. You pick a target, that target and every creature within a 20 foot radius of that creature must make a dexterity saving throw against your spell save DC. On a failed save a creature takes 10d6 force damage. On a successful save the creature takes half damage.

When you first cast this spell you can choose three of the follow effects. 

• No creature can enter. 
• Spell cost one less to cast. (example 2nd level spell cost 1st level spell slots)
• No creature can cast spells like demiplane or planeshift to leave your demiplane.
• You name one spell of 8th level or lower. That spell can't be cast within your demiplane.
• You can make difficult terrain in your demiplane.
• You can have the effect of Fly spell while in your demiplane.
• You can heal 10 hit points on the start of your turn while in your demiplane
• You can concentrate on one additional concentration spell while in your demiplane.

If two beings cast Domain Expansion in the same area. The creature that cast the first must make a charisma saving throw against the second creature spell save DC. On a failed save the second Domain cancels out the first one. On a successful save the first one stays and second on fails.

As a bonus action you can end the spell. if you cast this spell in the same spot for a year it becomes permanent.