I wouldn't get too excited about it.
Rly?
Polearm Master feat:While you are wielding a glaive,
halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attack from you when they enter the reach you have with that weapon.
Sentinel feat:When you hit a creature with an opportunity attack, the creature's speed becomes 0 for the rest of the turn.
Scenario:
Goblin attacks your Monk in meele ... it gets within your reach ... polearm master allows you to make Oppourtunity Attack ... you hit ... Goblin B movement is now 0, bcs of Sentinel feat ... your Halbeard have extra reach ... Goblin B cant reach you, therefore cant attack ... you make a 1 step back ...
The process is repeating, until Goblin is dead and you still have full HP, since it never got to you.
Effect:
Your character is litteraly untouchable in 1v1 combat.
