Allen is obviously made to be a parallel to Asta, Zenon's rival like Asta is for Yuno. However looking back, the other aspects of his character are mirrored and avenged by Magna.
Both Allen and Magna are common magic soldiers who mainly fight by conjuring weapons made of fire. Allen met his end fighting a devil and being killed by Zenon who in the process gained his belief that feelings and persistence are worthless without strength. However Magna got in the same situation as Allen, facing a powerful devil with his comrades' lives on the line. However Magna was able to pull of a win not through raw strength but his year of persistence developing his spell and his guts preventing him from falling to Dante's assault.
Wonder what Zenon would think if he had witnessed the fight.
Loyce: Of the main trio, Yuno's dad is the only dead parent who wasn't raised and someone Lucius is directly responsible for killing. Would also be a good way to get to Yuno who he viewed as a major hurdle to his plan. Plus, Sun Magic just fits well with the concept of angelic warriors.
Zara: Someone Julius greatly respected and as the first peasant knight, would be the perfect subject for Lucius to show how he'll make everyone equal. Could also so the inherent flaws in Lucius's plan since Zara's magic can't properly work if he has a high magical output.
Bonus points if you think they look better with their hair down.
Winter(RWBY): Normally wears a professional ponytail but gets her hair down during a fight with Cinder.
Magna(Black Clover): Normally has a simple mohawk but gets his hair down during a fight with his possessed rival.