Wrath of Yggdrasil

You open a gateway to the celestial plains. A 20-foot-radius sphere of blinding bright light and overpowering radiance appears, centered on a point with range and lasting for the duration. This area is filled with a cacophony of soft heavenly music and the creaking of wood that can be heard up to 30 feet away. No darkness, magical or otherwise, can enter the area, and creatures fully within the area are blinded.

The portal creates a warp in the fabric of space, and the area is difficult terrain. Any creature that starts its turn in the area takes 2d6 radiant damage. Any creature that ends its turn in the area must succeed on a Dexterity saving throw or take 2d6 force damage as silver roots and branches of Yggdrasil lash out at it.