Once per turn, when you make a melee weapon attack on your turn, you may opt not to roll and treat the roll on the d20 as 15.  If that attack hits, you may do one of the following.

• If you could grapple the target; knock them prone, or back 10ft
• Make another attack with the same weapon.
• Remove the target’s ability to take reactions until the end of their next turn.

You may use this feature up to 3 times, and it recharges after you finish a short or long rest.