Marvel: Starting with Dumbledore's Template at Kamar-Taj

Waking up in the year 2007—just before a certain billionaire builds a suit of armor in a cave—Ethan thought he had time to prepare for the approaching madness of the Marvel universe. He was wrong. Within seconds of his arrival, the Ancient One spots his multiversal anomaly and immediately "invites" him to Kamar-Taj. Fortunately, Ethan didn’t arrive empty-handed. Bound to the Multiversal Template System, he has the power to unlock the skills, bloodlines, and sheer power of the multiverse’s greatest figures. Starting with the unparalleled magical genius Albus Dumbledore, Ethan is about to turn Kamar-Taj's ancient rules upside down. Ethan knows the future. He knows the impending alien invasions, the heartbreaking sacrifices, and the tragedies written into the so-called "Sacred Timeline." And he has absolutely no intention of letting the script play out. Armed with an ever-expanding arsenal of multiversal magic, system-bought tech, and an absolute disregard for "canon," Ethan is going to save who needs saving and shatter the timeline in the process. The Avengers haven't assembled yet. Thanos is still biding his time in the stars. And the Marvel universe is entirely unprepared for a transmigrator who treats magic like a playground and fate like a suggestion. The timeline is about to be rewritten. And Ethan is holding the pen. — Description from novelcodex.org