Herculean Blow (5e Feat)
From D&D Wiki
- Your Strength score increases by 1.
- Three times per day you can exert yourself to the utmost, turning a successful melee attack into an automatic critical hit. The effort leaves you drained however, giving all adjacent enemies advantage to attack rolls against you until the end of your next turn.
You regain all expended uses of this feat when you finish a long rest.