author quite a good move taking the anti-hero route, he should also do some face slapping and keep the dark lord persona as after all this it would truly be surprising if the MC doesn't become ruthless and savage
author firstly cassia should have died as she is a OC not have impacted the timeline and some face slapping is needed . it would be no surprise if the MC goes eren Yeager on the wizarding world
author in the next chapter pls make Grindelwald teach these kidz and cassia a good lesson and send them to the hospital wing let them know actions have repercussions