Bladesong Master (5e Feat)
From D&D Wiki
- Choose a single one-handed piercing or slashing melee weapon. You can choose to use your Strength or Dexterity modifier for attack and damage rolls with this weapon.
- On your turn, when you score a critical hit or reduce a creature to 0 hit points with a cantrip or attack from your chosen weapon, you can make one melee weapon attack as a bonus action.