Blazaltation

One existing fire source bursts into a large conflagration for a moment. Each creature within 10 feet of the source takes 3d6 fire damage, or half as much with a successful Dexterity saving throw.

Alternatively, you can enhance a spell-casters affinity for fire. The next fire spell they cast gains either:

An additional +1 to hit and any related DCs are enhanced by 1.

Or has increased damage of an additional dice.

At Higher Levels:

For each spell slot used higher than 1st level, the spell does an additional 1d6 fire damage.

If this spell is used to enhance an spellcaster, they either get:

• Additional +1 to hit and +1 to the related DC, for each spellslot above first.
• Or has increased damage of additional die based on the level of the used spell slot.