When you take the Attack action with only a glaive, halberd, quarterstaff, or spear, you can use a bonus action to make a melee attack with the opposite end of the weapon that uses the same ability modifier as the primary attack and has a damage die of d4 (bludgeoning). While you are wielding a glaive, halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attack from you when they enter your reach.
Polearm Master - Bonus Attack: 1 Bonus Action
Polearm Master - Opportunity Attack: 1 Reaction