Among gods and alien-powered heroes, Batman is one of the few Justice League members without any superpowers - yet, he remains one of their most effective leaders. However, the Justice League once worked together to forge his Hellbat armor in the pages of DC Comics, giving the Dark Knight his own powers while handing him an armor so dangerous that he had to fight them to be able to use it.
Batman has worked alongside the Justice League since the group's formation, but one of the most contentious moments with the superteam came when he wanted to use the superteam-forged Hellbat armor. The armor was mighty, yet also incredibly dangerous, as gaining his own superpowers by wearing the armor slowly killed Batman by draining him of his metabolism. However, realizing that he needed a power boost to take down Darkseid, Batman decided to go against the Justice League's wishes and fight in the Hellbat armor. The result was one of Batman's deadliest but most powerful Batsuits ever.
In Batman & Robin #33 by Peter J. Tomasi, Patrick Gleason, Mick Gray, John Kalisz, and Carlos M. Mangual, Batman goes rogue against the Justice League after he wants to go off-planet to deal with Darkseid's incursions on Earth. However, the Dark Knight also wants to retrieve Robin's body on Apokolips and resurrect his fallen son. Batman tries to access the Hellbat armor at Justice League headquarters in space but is met with resistance from the superteam. Batman demands the use of the powerful armor he helped conceive alongside the Justice League, as its origins are revealed, as it was forged with each hero's specific powers.
However, after relenting against the Justice League, Batman would return to the JL headquarters and steal the suit again - being told by Lex Luthor (who was working alongside the team at the time) that it would drain him of his metabolism the more he used it. The Hellbat armor proves to be enough to stop Darkseid. Its advanced symbiotic-like A.I. tech lets him fly, shoot powerful energy blasts from his chest, withstand mammoth attacks, and have cloaking technology. After reviving Robin, Batman nearly dies himself, as the suit drains his metabolism to a near-lethal level.
Batman's Hellbat armor would appear in future DC Comics stories, but the hero's first time using it showed how dangerous and powerful it really was. It gave Batman his own powers and enough juice to stop Darkseid and save Robin. Although it nearly came with the cost of Batman's life, as even the Justice League tried to stop him knowing full well, it could kill him. However, like on most occasions, the Dark Knight's mission could not be stopped.