PHB

Create Bonfire

0-level (Cantrip) Conjuration

You create a bonfire on ground that you can see within range. Until the spell ends, the magic bonfire fills a 5-foot cube. Any creature in the bonfire's space when you cast the spell must succeed on a Dexterity saving throw or take 1d8 fire damage. A creature must also make the saving throw when it moves into the bonfire's space for the first time on a turn or ends its turn there.   The bonfire ignites flammable objects in its area that aren’t being worn or carried.
At higher levels: The spell's damage increases by 1d8 when you reach 5th level ( 2d8 ), 11th level ( 3d8 ), and 17th level ( 4d8 ).