Erevan's Elemental Glyph

Drawing inspiration from the Glyph of Warding spell, Erevan developed a variant that sacrificed some of the original's flexibility for a faster casting time. After all, angry Eldritch creatures are rarely patient enough to wait an hour for a spell that would harm them.

When you cast this spell, you inscribe a glyph that unleashes the power of an element. You inscribe it on a surface and it covers a circle with a radius of 20 feet.

The glyph is nearly invisible and requires a successful Intelligence (Investigation) check against your spell save DC to be found.

The glyph is triggered by a hostile creature that enters its area, or instantly upon casting if any hostile creatures are already in the glyph's area. When triggered, the glyph erupts with magical energy in a 20-foot-radius sphere centered on the glyph. The sphere spreads around corners. Each creature in the area must make a Dexterity saving throw. The effects of the sphere depend on the variant you choose when creating the glyph:

Elemental Burst. A creature takes 5d8 acid, cold, fire, lightning, or thunder damage (your choice when you create the glyph) on a failed saving throw, or half as much damage on a successful one.

Null Element. A creature's senses are temporarily numbed and it falls unconscious on a failed saving throw. 

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.