The events of Dark Nights: Metal pushed the heroes of the DC Universe to their absolute limit. This meant that Wonder Woman and Hawkgirl had to fight entire armies on their own, Raven pushed her mystical abilities to the edge and Superman headed into the Dark Multiverse to save his friend.
Along the way, Batman revealed one of the most dangerous built specifically for taking on Kryptonians. The Five Fingers of Death is Batman's equivalent of the Infinity Gauntlet, which mixes the powers of strange color-coded rocks from space as a single tool with truly awesome power..
The Dark Multiverse
Dark Knights: Metal by Scott Snyder and Greg Capullo saw the DC Universe attacked by the denizens of the Dark Multiverse. Led by the Dark God Barbatos (who has been influencing figures such as the Court of Owls and the Black Glove for centuries so they would open a gate to the Dark Multiverse,) the Dark Knights came into main DC continuity. A collection of corrupted Batmen from across different realities who serve Barbatos and his ambitions, the Dark Knights quickly prove too much for even the assembled heroes of the Justice League to combat head-on.
What made matters worse is that Batman was dragged into the Dark Multiverse when Barbatos escaped. The assembled heroes tried to counter the acts of the Dark Knights, and inadvertently played into the machinations of the Dark Knights, specifically the plans of the Jokerized Batman Who Laughs. Superman even rushes into the Dark Multiverse in an attempt to rescue Batman. But it's revealed that was another trap for the heroes. Superman was the true target of the denizens of the Dark Multiverse, who could use his solar-powered cells to help fuel the Great Battery that would drag the Earth into the Dark Multiverse.
Five Finger Death Punch
After luring Superman into the Dark Multiverse, Batman is confronted by a group of Supermen (including one who replaced Batman and another wearing a Lex Luthor armor.) But one the weapons held by the Superman who became Batman is a glove that this twisted version of Clark apparently doesn't recognize. In reality, it's a gauntlet that Batman designed to contain a number of different Kryptonite.
Snatching it away and donning it himself, Batman threatens the evil Supermen and claims that it contains every form of kryptonite that Batman possesses. Although they initially believed he wouldn't use it and risk harming his version of Superman, they back off and don't call his bluff. This gives Batman the opening he needs to pull Superman from the core of the battery and make their escape with the help of Daniel of the Endless, letting them have the chance to keep fighting.
The Kryptonite Powers
If Batman wasn't exaggerating when he claimed that the Five Finger Death Punch contained every kind of kryptonite, then he has a serious advantage against Kryptonian he comes up against. Batman specifically mentions that the gauntlet has both Gold and Periwinkle Kryptonite, two of the rarest forms of Kryptonite. While he usually keeps some Green Kryptonite around if he needs to weaken Superman, that's hardly the only kind he had. Red Kryptonite can weaken a Kryptonian just as much as Green Kryptonite if not more, while also forcing changes in behavior, turning someone heroic and kind like Superman into a brutal brawler. Blue Kryptonite doesn't have much of an effect on Kryptonians but weakens (and is even capable of killing) people from the Bizarro World.
Black Kryptonite has been shown having two powers: in the pre-Flashpoint DC Universe, it split a Kryptonian into two figures, one good and one evil. Introduced in the Dark Multiverse, a modified Black Kryptonite was shown to drive Kryptonians violently mad before killing them. Orange Kryptonite can give animals powers for 24 hour stretches. Gold Kryptonite can permanently remove a Kryptoian's ability to absorb and process sunlight into superhuman powers. Periwinkle Kryptonite causes Kryptonians to lose all inhibitions, making him more than happy to stop fighting Brainiac so he could flirt with Lois Lane.
Of course, the mere threat of Batman's Five Finger Death Punch was enough to get the multiversal Kryptonians off his back, and he effectively scared them away before he had to use it.