D&D 5th: Demon Tower of Madness
Casting Time: Swift
You can cast this spell when you hit with a melee weapon attack on your turn. Your weapon rings with thunder that is audible within 300 feet of you, and the attack deals 2d6 extra thunder damage to the target. Additionally, the creature must succeed on a Strength saving throw or be pushed 10 feet away from you and fall prone.
At Higher Levels: When you cast this spell using a spell slot of 2nd level or higher, the extra damage increases by 1d6 for each level above 1st.