Blast Wave

6th-level Evocation
Casting Time: 1 action
Range: Self (30-foot radius)
Components: VS
Duration: Instantaneous

You call into existence a ring of fire that quickly spreads from you to envelop all nearby creatures and objects. Each creature within 30 feet of you must succeed on a Dexterity saving throw or take 6d8 fire damage and continue to burn, being lit on fire. This fire deals 3d8 fire damage instead of the normal damage for being set ablaze. While creatures burn from this effect, their movement speed is halved. A creature that succeeds on it saving throw takes half as much damage and isn't set on fire.
The spell catches nearby items ablaze, but causes no pressure.
At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the damage (both initial and from the burning condition) increases by 1d8 for each slot level above 6th.

Source: Homebrew