The Artist Who Paints Dungeons (The Painter Who Draws Dungeons)

Why, seems like I’ve become a haunted portrait. —— Manhwa Synopsis: A world forever changed by the "Great Cataclysm." Seo Jio, a former art teacher, dies in a sudden fire, only to be pulled into a portrait and become part of the painting itself. Within the world of the portrait, Jio gains godlike powers that allow him to create life and even open gateways to other dimensions. Through his abilities, Jio encounters countless people and tries to help them overcome the problems they face. However, the more he crosses dimensions and resolves the incidents he encounters, the closer he comes to uncovering the truth hidden behind his own death... — Description from novelcodex.org