Wave of the holy Sun

You conjure up a burning and holly wave of sunlight and fire that from yourself. The area can be up to 50 feet long, up to 20 feet thick, and up to 40 feet tall. Each creature in that area must make a Wisdom saving throw. On a failed save, a creature takes 6d8 Radiant damage and 4d6 bludgeoning damage and is knocked prone and blinded for 2 rounds. On a successful save, a creature takes half as much damage and isn’t knocked prone but still slightly blinded so all attacks for the next 2 turns are at disadvantage. The wall of radiant sunlight then spreads out across the ground in all directions, boosting flames and everything is illuminated in its area and within 30 feet of it, for 12 seconds.

Additional: Any dead, undead, abomination and fiends take an additional 5d4 radiant damage. And any creatures that have hit points of 20 is automatically killed. 

High level: At level 5, Damage is now at Radiant 8d8 and 6d6 bludgeoning

Higher level: at level 7, the Damage is now Radiant 12d8 and 10d6 bludgeoning- All allies caught in the wave gains 2d4 heating points and each melee weapons deal +10 radiant damage for 2 minutes. 

Higher Level: At a level 9 or higher. The wave now travels in a dome from you reaching 300 feet radius, and the wave turns into sacred ground. And the Damage is now pure Radiant 5d20+20. And any undead with less than 40 hit points are vaporised. And all creatures take 3d6 damage at the start of each turn they are in the radius. And the dome stays up for 5 minutes. All creatures have disadvantage on all attacks, and all allies have advantage with +7 on wisdom, intelligence and constitution checks and saving throws.