As an action, make a weapon attack.

On a hit, add 2d8 + your spellcasting ability fire damage to the attack’s damage roll and the creature is burning 1.

On a critical hit, add twice as much damage.

On a miss by 4 or less, add half as much damage.

Augment

You can increase the damage by 2d8 and the burning level by 2 for each additional mana expended.