One way I did it was to create an ability of type "Effect Target".
I had this ability have a "Launch Missile" effect which on impact triggered a "Create Persistent" effect.
Still with me?
For this last effect ("Create Persistent") I had the "Periodic Effects" field point to a "Create Unit" effect.
I also set the "Search - Reveal Flags" and "Search - Reveal Radius" fields on the persistent effect to "Unfog" and "5" respectively.
It was a whole lot more complicated than that, but it's a general idea, I hope it's kind-a helpful anyway.
@Frmlol: Go
Is your flare ability an "Effect Target" ability?
One way I did it was to create an ability of type "Effect Target". I had this ability have a "Launch Missile" effect which on impact triggered a "Create Persistent" effect. Still with me?
For this last effect ("Create Persistent") I had the "Periodic Effects" field point to a "Create Unit" effect. I also set the "Search - Reveal Flags" and "Search - Reveal Radius" fields on the persistent effect to "Unfog" and "5" respectively.
It was a whole lot more complicated than that, but it's a general idea, I hope it's kind-a helpful anyway.