The phrase "run the gauntlet" is used to describe an experience where someone faces a series of challenges or obstacles in succession. Some synonyms that can be used to convey a similar meaning include "face the music," "brave the storm," "endure the fire," "take a beating," "go through the wringer," and "run the obstacle course." Some other idioms that can be used to describe a similar experience include "face the music," "bite the bullet," "bear the brunt," and "take the heat." Regardless of the phrase used, the idea behind all of these idioms is that someone is undergoing a difficult experience that will test their strength and resilience.