Isekai of the Ultimate Ritualist

Ishrin was the most powerful being in the world. He stood at the top as the most powerful ritualist that there ever was, and he was ready to perform one last ritual to become omnipotent. maybe with this he was going to be powerful enough to bring back the girl he loved.
However, right as it was about to perform this last ritual something went wrong. He was suddenly transported elsewhere, by an unknown god, and what was even stranger was that this god claimed that it was a mistake. That he wasn't supposed to be there.
He seemed genuinely sorry, and he offered something in exchange for the trouble. Of the many things he offered was also the promise that one day Ishrin might be able to see his wife again. The deal was simple: he would be reincarnated in a fantasy world, where he could live out his life however he wanted. A vacation, the god said. And at the end of this vacation was his wife.
Ishrin didn't have any choice but to accept, but to be honest he didn't feel like it was a bad deal. All his doubts will finally cleared when the god offered him to keep his old stash of ritual materials.
And so, Ishrin’s adventure in the new world begins.