Perhaps there could be an indicator on the cursor whether certain feats will work with the shot. Like: "95% - (ambush)"
The overall illumination of the target is what counts, regardless of the source(s) or color of the light (though colored lights provide less overall illumination).Please do. Those of us with less than perfect eyesight have problems with the subtle gradients of light in the game.
I agree it's sometimes hard to tell if the ambush will trigger so I might add the suggested indicator when targeting.