Nice idea!
I have a habit to (usually) target a specific creature if I care.
One useful point would just be if the "random" target and/or typical default (there's a discussion about this going on) was the last instead of the first creature. It could still happen where you try to cast a spell at the wrong target, but now you need one creature to enter and another to leave in a very short window, which would probably be a low enough probability to satisfy me.
This assumes the default/random target is actually always the first creature. Either way, I think it would be nice if it defaulted to the last one.
Would this be good enough for your stated issue?
The deathbot will come back eventually.
>Daid: Pretty sure you have a whole big bucket as your penny jar. You never have only two cents. :p