MC falls through a dimensional warp of some sort. Comes to in a slave wagon along with fairy princess and others. Manages to escape and sets them all free. His game role-playing on Earth translates into powerful magic here. Is able to read ancient magical text.
I just spent most of the evening going back through all of my history back to the beginning of 2018, and didn't recognize anything. Tried search but no go. Anyone have any ideas?