Heavy Arms Mastery

When you take the Attack action with a glaive, halberd, quarterstaff, or spear, use a bonus action to make a melee attack with the butt of the weapon; use same ability modifier as primary attack.

Damage die for this attack is a d4, deals bludgeoning. When wielding a glaive, halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attacks when entering reach.