You are still butthurt about Gaban being equal to Rayleigh?
1- Even if they can't be killed, they can be damaged and hurt. Thats the point he was making, they can be hurt by CoC attacks. They don't need to kill them to defeat them.
2- He also said he was ''rusty'', if his attack worked as he expected he wouldn't say that. Meaning, in his prime he could do better.