Baam, Khun and Rak vs Reflejo
So to sum it up. Reflejo is a cool and calm man who offered his services to help and lead Baam's goal. However, he's later revealed to be the main antagonist of the Workshop Battle Arc. Behind the mask, he's insane, cruel, prone to anger and lacks a fear of death because he welcomes the day he dies ever since he lost everything he loved long ago as a servant to a princess. It turns out his true goal was to turn Baam into a weapon at the orders of his boss and Reflejo, although insane, went very prepared for this fight.
He inheritied a piece of his boss's power that renders him more like a shadow, boosting his strength from that of a D-Ranker to somewhere over a B-ranker which is insane if you know the lore. He studied Baam's personality to look for weaknesses, finding out he values the lives of his friends more than he does himself. So what he does is he defeats three of Baam's friends, all very OP characters not to be underestimated and uses the red witch Hwa Ryun as his hostage because of her pocket, a communication device. He uses her as a shield, knowing Baam won't risk hurting her making the fight all the more difficult. Baam has to team up with Khun and Rak to save Hwa Ryun, defeat the OP Reflejo and get the heck out of there because he planned to destroy the battlegrounds if he ever lost. As I said, this guy came very prepared and this is an intense fight.
What I love about this fight the most is that not only are they going up against a kind of smart opponent they've never fought before but we also get to see Baam reunited with his best friends from Part 1 to defeat this villain and save the person who has been by Baam's side the longest.