Hogwarts and the Holy Grail War

Ethan, a time traveler who was admitted to Hogwarts School of Witchcraft and Wizardry as an exception, discovered that his talent seemed to be a little bit higher than that of others, and he could also use legendary ancient magic.
Thus, his career of causing trouble in the magical world began.
What is this? A black-hearted Holy Grail tainted by black mud? Chop it up!
What is this? A bald dark wizard with no nose? Cut it off!
What is this? The ghost of the big boss from the last century? He has been liberated!
What is this? An ancient secret treasure hidden beneath the academy? It's mine!
After a not-so-intense battle, Ethan looked at the enemies falling in front of him with a look of disdain.
"You fell down before I even tried."
-
"As bright as daylight and blinding, disarming you and eliminating the threat, knocking you out and controlling you, what a perfect combo!" Ethan, the former head Auror who retired early and stayed at home to slack off, shared his experience with reporters.
"What if this approach doesn't work?" the reporter asked.
"It's very simple, my friend." Ethan said comfortably with a smile on his face.
"Just use Avada Kedavra on him."
Note: This book contains a lot of secondary settings, ooc characters, and a modified timeline, so please read on with caution.