Blue Flame Blade

You brandish the weapon used in the spell's casting in blue flames and make a melee attack with it against one creature within 5 feet of you, strikes leave a trail of flames. On a hit, the target suffers the weapon attack's normal effects and then becomes wounded by burning heat.

The target has to succeed on a Constitution Saving throw against your Spell-Save DC. It takes 1d10 fire damage on a failed save or half as much on a successful one, and the spell ends.

This spell's damage increases when you reach certain levels. At 5th level, the melee attack deals an extra 1d10 fire damage to the target on a hit, and the damage the target takes for save fail increases to 2d10. Both damage rolls increase by 1d10 at 11th level (2d10 and 3d10) and again at 17th level (3d10 and 4d10).