No indication that the attack is limited, but I'm 90% sure the implementation is broken. It's a nice idea but desperately needs some indicator that it's going to happen - simply dying because you tried to kill a monster but the attack decided to not work is not fun.
I never managed to kill anything. The attack only worked for me at the start, then it never worked again. Jumping (without attacking) disabled all future attacks. Clicking the window ... disabled all future attacks. Standing within 6 feet of any monster was randomly 50/50 instant death. I gave up after about 15 attempts to get past the first monster :(. I don't know if I was doing something wrong.