WARNING: The following contains spoilers for Black Clover Chapter #282, “Black Guardian,” by Yuki Tabata, Taylor Engel and Annaliese "Ace" Christman, available now in English from Viz Media.
Chapter #282, “Black Guardian,” of Black Clover finally debuts the Devil Union between Asta and Liebe and, thankfully, their first battle demonstrates how effective their anti-magic is against the super-charged, ancient devil. Everyone is relieved that Asta and Liebe triumph, but Gimodelo’s warning about Nacht’s current status could point to the vice-captain’s eventual death.
Asta and Liebe’s Devil Union, Black Guardian, is a big step up for Asta. Seeing all of his friends and allies rooting for him is no surprise, but watching his biggest critics cringe at his success is the icing on the cake. Asta has received much criticism in the past from several Clover Kingdom Knights about "not having the talent" to become a true Magic Knight. Now, they're forced to sit back and watch as the young, talentless peasant comes to their rescue.
Black Guardian neutralizes the ancient devil's condensed mass of magical energy with ease. The other Magical Knights could only redirect the attack, but Asta completely cancels it. Since there was no struggle, Asta and Liebe proved that they no longer have anything to fear from powerful devils. Even Mereoloena couldn't defeat any of the ancient devils, though she was able to keep it occupied well enough.
With the current battle setup, Asta and Liebe will have to rush to make it to the Spade Kingdom to save the Clover Knights. The two higher-up devils are extremely powerful, and they know it. The pair toy around with Nacht’s life and, unfortunately for Nacht, only can devise a plan to distract them and defeat Morris, putting a stop to the ritual. But Nacht won't abandon Jack, either, and his plan might lead to him sacrificing himself to allow Jack to escape. Regardless, Nacht’s life is currently in danger, Asta is miles away and the other Magic Knights are preoccupied with the devil invasion.
Nacht still has one Devil Union up his sleeve that could prove useful. He did witness Asta and Liebe’s first Union, so he may have picked up a trick. Also, since Nacht is the vice-captain of the Black Bulls, it's his duty to make sure the team is always safe, including the captain. With all the buildup for Asta’s return, the story has set up Nacht’s sacrificial death as well. From him admitting that the Clover Kingdom’s mages are stronger than he anticipated, to him showing faith in another person, Asta, Nacht’s personal development over the past chapters has humanized him quite a bit.
It would not be shocking to see Nacht sacrifice himself to allow Asta and Liebe to be the heroes of the war and ensure the survival of the human race. Nacht’s number one goal is to stop the invasion of the devils, and seeing that they are currently running amok, his efforts are only failures. Still, having Asta and Liebe on the battlefield has changed the tide of the battle, but their five-minute flaw is going to be the deciding factor of the overall victory.