You have mastered a number of combat stances, allowing you to switch up your tactics in battle.You have a number of stance points equal to your proficiency bonus, you regain these stance points during a short or long rest, and regain one stance point when you score a critical hit.As a bonus action, you can expend one of these stance points, and assume a stance of your choice for one minute, or until you start a new stance.You must concentrate on these stances as if they were spells, and if you would fail a concentration save, you can expend 1 stance point to make it succeed.The stances you can assume are listed below.

Defensive stance 

While in this stance, your AC increases by 1, and you have advantage on strength saves.

Offensive stance 

While in this stance, you have add +1 to your attack and damage rolls.

Critical stance

While in this stance, your attacks score critical hits on a 19-20, and your critical hits deal an extra die of damage.

Mobile stance

While in this stance your speed increases by 10 ft, and opportunity attacks against you are made at disadvantage