WARNING: The following contains spoilers for Avengers #41 by Jason Aaron, Javier Garron, David Curiel & VC's Cory Petit, on sale now.
The Phoenix Force is one of the Marvel Universe's most powerful entities, and now it's looking outside the usual roster of telepaths that have attracted it in the past for a host. Many Avengers, their allies, and even some villains have been given the chance to fight and prove their worth with one relatively obscure member of the Agents of Wakanda revealing he really wants that power.
American Eagle is giving it his all to fight for access to the full power of the Phoenix Force, and he just made it clear he's willing to beat down his fellow heroes if necessary to do it.
American Eagle is one of the many Marvel figures who has been pulled into the White Hot Room by the Phoenix Force. The cosmic being is seeking a new potential host, and has decided to throw these candidates at each other to see which one is truly worthy to become bonded with the Phoenix. American Eagle is luckily a largely altruistic figure, so him gaining that power wouldn't pose a massive threat to the world like Namor, Red Widow, or the Orb likely would. For many of the heroes, gaining access to the Phoenix is a better victory.
This doesn't mean he's going to just give up the chance to gain all that power, however. American Eagle is pitted against Luke Cage for their duel, and both men -- like the other people involved in the challenge -- are empowered somewhat by the Phoenix Force. While Cage is tempted, the Harlem-based hero ultimately decides that he doesn't truly want the power of the Phoenix Force. But American Eagle reveals that he does want such a monumental power boost, in part by laying into an unsuspecting Cage with a Phoenix-empowered punch.
Jason Strongbow, aka American Eagle, first appeared in Marvel Two-In-One Annual #6 by Doug Moench, Ron Wilson, Gene Day, George Roussos, and Pierre Bernad Jr. After a battle with the supervillain Klaw, Strongbow was imbued with a radioactive element that granted him enhanced strength, speed, endurance, and durability. Working together with the Thing, Ka-Zar, and Wyatt Wingfoot, American Eagle proved himself to the other heroes, but quickly shifted back into a smaller role as a hero in Arizona.
American Eagle reappeared in the aftermath of "Civil War", coming into conflict with the Thunderbolts as an unregistered vigilante. However, his status as an officer for his Navajo reservation gave him immunity from suffering any legal consequences for his actions. Recently, he's been one of the heroes recruited to the Agents of Wakanda, allowing him to operate more openly and consistently with other superheroes.
During the fight between Cage and Longbow, the focus is put on how the Phoenix Force has been drawn to American Eagle less because of his fighting prowess, and more because of his inherent passion. As a proud member of the Navajo Nation, American Eagle has the kind of drive that draws the Phoenix. It's a consistent attractor for the Phoenix Force, with the power often coming to those whose force of will can impress it. American Eagle proves himself a worthy candidate by utilizing powers quickly, fighting on even after breaking some of his knuckles against Cage. It's a powerful moment for American Eagle and could set him up to become a worthy new wielder of that legacy.