Brandenfyre's Unleash the Inferno

You unleash a vast amount of heat from your body. For the next minute, all creatures within 30 feet of you must make a CON save at the start of their turn. On a failure, a creature takes 6d12 fire damage, has its movement speed reduced by half, and suffers the effects of one hour of extreme heat. This damage decreases by 1d12 for every 5 feet the creature is away from the caster. On a success, a creature takes half the damage and does not suffer the effects of extreme heat. 

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d12, and the range increases by 5 feet for each slot level above 4th.