Blood Domain Expansion - Holy Bleeding Shrine

Roll a D100, succeed: 51-100, failure: 1-50. To cast this spell, the user must slash both their wrists dealing 20 slashing damage (somatic). Upon success of the d100 roll, all creatures within a 100 ft radius are transported to a demiplane much similar to the Blood plane except it is only 100 ft in diameter and there is a throne made of of an unknown material that is indestructible and constantly bleeding, the throne sits atop a hill of bones, all creatures in the demiplane except for the caster are tethered to the ground my chains made of blood and have their blood drained through their mouths, eyes, and wrists, all creatures in the demiplane except for the caster take 5 d10 of necrotic damage if they are level 10 or below, 10 d10 of necrotic damage if they are level 11 or above, all creature in the demiplane except for the caster have the option to make a constitution saving throw, if they succeed then damage is halved, if the fail then damage is doubled, if the caster is below half health they are healed up to half health. Upon failure of the d100 roll, all creatures within range are transported to the demiplane, are not chained down, do not have their blood drained but instead are free to roam the 100 ft demiplane essentially turning it into an arena.