You conjure a spirit from the Upper Planes, which manifests as a pillar of light in a 10-foot-radius, 40-foot-high Cylinder centered on a point within range. For each creature you can see in the Cylinder, choose which of these lights shines on it:
Healing Light. The target regains Hit Points equal to 4d12 plus your spellcasting ability modifier.
Searing Light. The target makes a Dexterity saving throw, taking 6d12 Radiant damage on a failed save or half as much damage on a successful one.
Until the spell ends, Bright Light fills the Cylinder, and when you move on your turn, you can also move the Cylinder up to 30 feet.
Whenever the Cylinder moves into the space of a creature you can see and whenever a creature you can see enters the Cylinder or ends its turn there, you can bathe it in one of the lights. A creature can be affected by this spell only once per turn.
Using a Higher-Level Spell Slot. The healing and damage increase by 1d12 for each spell slot level above 7.
Unless you cast this with Wish; it is exclusively a Cleric spell.
Well, goodbye Tarrasque, enjoy your long and painful death
But the ironic thing is that Mordenkainen's Faithful Hound deals 86400 force damage and is fourth level!
Mechanically this is a great spell and I get that they wanted to limit any kind of spell that summons actual monster statblocks which is why they included the summon spells to summon singular creatures with balanced statblocks instead, but this really should've just been a new spell entirely with a different name.