I think it should be like other targeted ults are now and how it used to be. It would say, "No targets in range" when you use it and it can find no players in range with no sound, "Player has immunity" when the target has immunity and makes the failed ability sound, or "x players effected". I believe this is how Orc works already also. Currently it does not tell you if there is still a player with immunity in range as well as who it targets, though you could implement it that way if you want to give the ult even more power (or give it to all targeted ults to reduce the power of lace--not sure if you would want to do this, but the option is there ^_^).

Alternatively, you could take out the player has immunity if you wanted to increase the power of the ult--though then you would have to do it for other races, such as Orc.

At the very least, the sound is horrible in it's current state as when you press it even when there is no one nearby you get that beep. When you press it like I do pretty often, it is just about all you hear