You manifest 3 small, sizzling fires that each occupy 5ft that are in range. Until the spell ends, for every turn on initiative count 10, those who are in a 15ft radius from a fire must succeed a constitution save or take damage equal to the appropriate distance; If a creature is 5ft away from an ember they take 1d12 damage, 10ft away means they take 1d10 and 15ft away means they take 1d8.
If you successfully make the save to maintain the concentration on the spell, each fire expands in a random direction determined via a d8 for each, if the ember cannot successfully move in that direction due to there being a wall or barricade, the ember does not move.
At Higher Levels: When you cast this spell using a spell slot of 2nd level or higher, the amount of dice rolled for appropriate distance is increased by 1.