Holy Knights of Liones vs. New Generation Holy Knight/Demon Hybrids is a battle between the entire Holy Knights of the Kingdom of Liones and the New Generation Holy Knights turned Demon hybrids by Hendrickson.
After recovering from defeat by Gilthunder through the Black Mark, Hendrickson made his move by destroying the castle in one swipe, sending those caught in his attack flying and used Blood Awaken to cause the New Generation's Demon blood to run out of control and mutate them into Demon hybrids starting with Muramo, starting a rampage throughout the capital of the kingdom, leaving the Holy Knights and knights in complete confusion of what's going on.
After witnessing the New Generation suddenly mutate into Demons and started rampaging, the Holy Knights, as well as knights, battled them almost immediately in defense of the kingdom and multiple skirmishes broke out in almost every sector of the kingdom's capital including at the ruined castle.
However, the Holy Knights started to suffer heavy casualties as one-by-one they fell before the ferocity and fierceness of the Demon hybrids' malevolent and terrifying powers and the Demons continued to destroy everything in their path. But few Holy Knights managed to kill several of them during the skirmishes.
Meanwhile, the other Holy Knights and knights led the full-scale evacuation of the entire population away from the war-zone while fighting off any Demon hybrids who would dare try harming the civilians.
As the Holy Knights continue to fight desperately against the Demon hybrids, they were aided by Ban and King of the Seven Deadly Sins who dynamically worked together taking out the strange "plant" creatures from the affected New Generation's bodies and revert them back to normal after Jericho was saved by the same method.
After Ban and King cured the New Generations and headed to Merlin's ruined old castle to fight Hendrickson. The Holy Knights who rallied themselves, recovering from their losses, later joined up with the Seven Deadly Sins as they surrounded the castle like they did ten years ago, but this time, to Hendrickson as they now know who the true enemy is, preventing the Great Holy Knight's escape while the Sins battled Hendrickson.