WARNING: The following contains spoilers for Black Clover Chapter #289, “Freezing Sun,” by Yuki Tabata, Taylor Engel and Annaliese "Ace" Christman, available now in English from Viz Media.
The devil infiltration of the human world has given birth to a new threat in Chapter #289 of Black Clover, "Freezing Sun." Asta’s new devil union with Liebe is proving to be effective against the devil problem, but the high-level devils, Lilith and Naamah, have just thrown a curveball Asta’s way.
Asta is able to defeat one of the devils, but right before the body disappears its twin counterpart merges with the deceased one to form an entirely new entity. This union between devils is not only troubling, but it could also be indicative of immortality. Asta is also racing against the clock, and if the devils are able to merge with one another after their deaths, the Dark Triad could be an even bigger threat than first anticipated. Based on the details revealed in Chapter #289, let's break down how devils could gain the upper hand in the battle against humanity.
Lilith and Naamah are high-level devils, but following the death of Naamah, Lilith has unlocked their true power with a new devil union. It is still unclear whether or not only the high-level devils can form a union with one another, but that detail alone is troublesome enough for the Magic Knights. Nacht claims that the new form of the two fused devils possesses more magic than simply adding the two host together, meaning that their unison has created a new beast entirely. Luckily for Asta, he can’t feel negative magic steaming off the new devil.
Since Naamah was killed, the devil's magic should have been eradicated, but Lilith sealed it in time and utilized it for the union. Devils operate differently from humans so their prolonged existence after death could become a type of magic -- one that can be utilized by another devil. Inherently, this could give the devils an aforementioned form of immortality. Most likely, only high-level devils can use this ability, otherwise, there would have been instances of lower-ranking devils performing the same unions to overpower the higher-ups in the underworld.
Gaining immortality in this way could be the ace the Dark Triad is hoping for. If some devils are able to form a union with each other, the three that are corrupting the Dark Triad are probably going to form more at some point in this battle. This means that once the human host is no longer able to serve a purpose, Lucifero and his minions could somehow create their own union to prolong their life. The Dark Triad is clearly being manipulated by the devils, and once their devil companions are able to fully manifest in the human world, it wouldn’t be surprising if Zogratis fell by their hands.
Asta has the upper hand against the new devil union because of his anti-magic, but does that mean the union between devils and humans is stronger than the union between devils? The Dark Triad formed unions with their devil counterparts simply because the devils could not manifest in the human world... yet. Their need to take advantage of each other is what caused them to form unions. When it comes to Asta and Liebe, their sibling connection -- through Licita -- is what allows their union to be inherently strong. It seems like devil unions are completed by the means of both parties sharing a common goal, but the unions' true strength derives from the actual link between both parties. Therefore, even if the Dark Triad has formed unions with the strongest devils from the underworld, their true compatibility will always come short compared to Asta and Liebe.
Even so, devils forming unions with other devils will give birth to new magical foes that are out of this world in Black Clover. Asta’s biggest constraint right now is the time limit on his union with Liebe, but when it comes to overall strength and compatibility, Asta and Liebe will come out on top.