You brandish your hand and summon a whip made of flame. When you cast this spell, select a target within range and make a ranged spell attack against it. On a hit, the target takes 1d4 slashing damage plus your Dexterity modifier and 1d6 fire damage, and it has to make a strength saving throw. On a failure, the target is restrained for 1 round unless it succeeds a strength check against your Spell Save DC on its next turn. 

At higher levels: When you cast this spell using a spell slot of 2nd kevek or higher, the fire damage increases by 1d6 for every level above 1st.