Claim Lair

By placing your personal wealth within an area and invoking the dragon’s territorial nature, you claim the area as your lair, imbuing you with extra power within its confines. You can claim an area of up to 2,500 square feet (a space 50 feet square, or one hundred 5-foot squares, or twenty-five 10-foot squares). The claimed area can be up to 20 feet tall and shaped as you desire. While within these confines, you can take one of the following lair actions once per round on initiative count 20:
• Magical darkness spreads from a point you choose within 30 feet, filling a 15-foot-radius sphere until you dismiss it as an action, use this lair action again, or die. The darkness spreads around corners. A creature with darkvision can’t see through this darkness, and nonmagical light can’t illuminate it, but you can see in the area as if it were brightly lit. If any of the effect’s area overlaps with an area of light created by a spell of 2nd level or lower, the spell that created the light is dispelled.
• Part of the ceiling collapses above one creature you can see within 60 feet of you. The creature must succeed on a Dexterity saving throw against your spell save DC or take 3d6 bludgeoning damage and be knocked prone and buried. A buried target is restrained and unable to breathe or stand up. A creature can take an action to make a DC 10 Strength check, ending the buried state with a success.
• A tremor shakes the lair in a 30-foot radius around you. Each creature on the ground in that area other than you must succeed on a Dexterity saving throw against your spell save DC or be knocked prone.
You can take an action to dismiss this spell.