You have done extra training and become a specialist in a specific type of weapon.

Polearms: Glaive, Halberd, Pike, Quarterstaff, Spear, Trident

You must be proficient with the weapon you are using to gain the benefits listed below, and you must be proficient with at least one weapon in the group listed above in order to take this feat.

• When you take the Attack action and attack with one of the weapons listed above, you can use a bonus action to make a melee attack with the opposite end of the weapon. This attack uses the same ability modifier as the primary attack. The weapon’s damage die for this attack is a d4, and it deals bludgeoning damage.
• Vigilant Defense. While you are wielding a polearm, other creatures provoke an opportunity attack from you when they enter the reach you have with that weapon.