Polearm Master

You gain the following benefits:
* When you take the Attack action and attack with only a glaive, halberd, or quarterstaff, you can use a bonus action to make a melee attack with the opposite end of the weapon. The weapon’s damage die for this attack is a d4, and the attack deals bludgeoning damage. This attack uses the same ability modifier as the main attack.
* While you are wielding a glaive, halberd, pike, or quarterstaff, other creatures provoke an opportunity attack from you when they enter your reach.
Appears In: 5e Players Handbook