Burn

Weaving a pinch of sulphur through the air you speak the word for burn in your native tongue, and you choose one target you can see within range. It must make a dexterity saving throw or take 12d8 fire damage as a burst of flame engulfs it and at the start of the creatures turn until it uses an action to douse the flame, they take an additional 4d8 fire damage half as much on a success and they are not set aflame. 

While on fire, the creature cannot cast spells that require material components and ranged attack rolls are made at disadvantage.

At higher levels, the damage increases by 1d8 on both damage rolls for every level above 7th.