Everfallen

As a fehru-alchemist, Dave should not exist, but then, a lot of things should not exist. After a disturbing turn of events, Dave finds himself returning to Rhi-Daton, the very city he escaped from years ago. Meanwhile, a strange woman with mysterious powers joins forces with the merciless House Dawn to intercept a peculiar weapon before it falls into the wrong hands. Things take a turn for the worse when the city unexpectedly closes its gates. Trapped inside with no way out, Dave runs into Leto, a fellow alchemist. Together, the duo must uncover the secrets of the past and prevent the disaster from unraveling further than it already has.

(Source: Webtoon)