Polearm Master

You can keep your enemies at bay with reach weapons. You gain the following benefits:

• When you take the Attack action and attack with only a glaive, halberd, spear, 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 primary attack.
• While you are wielding a glaive, halberd, pike, spear, or quarterstaff, other creatures provoke an opportunity attack from you when they enter the reach you have with that weapon.