I tried to do it with volume scatter but result was ugly and strange. Today I found the solution: I make mesh and add emission shader to volume but after sompositing this light disappears. I want try to make animation with rotating light. Is there any way to make cool light?
The light is being lost at the point where you multiply in the Ambient Occlusion as that pass doesn't include the 'light' since it's purely emissive. One solution would be to activate the Emission pass in the Render Layer properties and then Add it in as shown (Emit connected to an Add Color node) :