Not sure on the mechanics of the game...

If you're using IS Boxer, you could do a Send Next Click action.
And set it, so the click is ignored in the current window.

Then press whatever hotkey, to activate your ability.
And just mouse click immediately, or very quickly.
You wouldn't have to leave your current window to do this.

I know if Warcraft, if it is a ground-target spell, there's no way to do the "aim at your feet".
But the Send Next Click action is quite fast and easy.