How can I light up this wall as if reflections from a fire? sort of a dancing light on the wall? I tried with an emission surface with a wave texture and colour ramp. but it doesn't seem to work. Any other suggestions? enter image description here
Rather than trying to emit flames onto the wall, animate the flame texture and mix it into the wall material.
Here I animated the z-location of the mapping node to "move" the wave texture and then multiplied it with the wallpaper colour.
Note that from 2.81, or daily builds until then, some of the texture nodes now have a time factor so we can properly animate the textures instead of moving through them using the mapping node.