Magus in an Apocalypse World

In the Recorded Year of 2050, Two and a Half Decades since the Start of the Apocalypse. The  Whole Human Civilization has been wiped off the World. Only Ruined Buildings that formed its former Glory. The Last Stronghold of Humanity fell to the Apocalypse, and the Last Humans in the Planet fought against the Apocalypse Alone. The ones that died first were lucky to have not seen the Current World. It was Horrifying... A man was fighting against the Undead from a High-rise Building Rooftop. He was cornered as he had nowhere to go. The Last Human City fell, and the only thing that was left for him was a Wasteland. His name was Arthur Ironhearth, The Last Human Survivor. He was surrounded by an Undead Horde that resembled a Sea of Bodies with no End. He didn't want to give up, but the future in front of him was a Cliff heading to Damnation.  He wanted to kill himself before the Undead eats his Body. He pointed his Rifle to himself, and as he was about to pull the Trigger. A Book from his Backpack shone in an Illuminating Bright Light. It was the Magus Book, The Random Book he found in a Store. It was abandoned, but it looked interesting, so he took it. Never did he thought that such a book would have power. The Bright Light illuminated the High-rise Building, and Arthur found himself closing his eyes in fear. The moment Arthur opened his Eyelids, He found himself in a Nostalgic Scene. In the Recorded Year of 2025, An Hour before the Apocalypse falls upon the World. A Third-Year Highschool Boy woke up from his nap with a shocked expression. He was Arthur Ironhearth, The Last Survivor that managed to Survive until the End. The Holder of the Magus Book. And the Future Magus in an Apocalypse World. [Be warned that the MC is Ruthless.]