Domain Expansion: Eldritch Garden of horrors

After casting, a large eldritch garden of the (casters choice in terms of appearance) springs fourth as an 80ft cube. Enemy's caught inside need to make an Intelligent saving throw (equal to the warlocks charisma DC) on fail they will take 10d12s psychic damage or 7d12 on a success. swarms of demonic entity's then flood the area instantly causing 6d12s of psychic damage to any enemy's moving in the domain in that turn. Any enemy who do not move within their turn take 9d12s of psychic damage. 

Anybody except the spell caster caught in the domain dont know were the border of the domain is and cannot see outside. You suffer 1 level of exhaustion after the spell ends.