Vestige of Ugar

You create a zone of burning light that lasts for 1 minute, or until you lose concentration. The area is a 15 ft. cube. Any creature that enters or starts its turn in the zone must succeed on a Constitution save or take 2d10 fire damage, half as much on a successful one.

Creatures in the zone gain no benefit from 1/2 or 3/4 cover and they cannot hide.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the zone increases in size by 10 feet for every two slot levels above 3rd.