Sentinel at Death's Door

At 6th level, you gain the ability to impede death's progress. As a reaction when you or a creature you can see within 30 feet of you suffers a critical hit, you can turn that hit into a normal hit. Any effects triggered by a critical hit are canceled.

You can use this feature a number of times equal to your Wisdom modifier (minimum of once). You regain all expended uses when you finish a long rest.