Sythen: We are looking for a mysterious/depressing mood. Something that envoke the idea of a place where this magician left his memories/tricks. Thanks for the feedback on the light =)
Don't use the specular option in UE4 for your average specular textures, it's not going to work like how you expect it to, and it's mostly left in for legacy purposes.
activate the image bounds put the cursor to 0,0 drag the uvs to the bottom-left corner use the cursor as manipulator and scale until the uv touch the bounds