What need to happen that Batman/Bruce find self in situation to kill the Joker ?

He already kill his sidekick, put one other in the wheelchair, mess with his Bat family almost make them gonna insane...and who know what else... so... what he (Joker) have to make that Batman go mad and kill him ?

@arkhamwrath: Batman vs Joker comics to stop selling.

Batman was going to kill joker after he killed Tommy Elliot. He was actually doing it. He only got stopped because Gordon happened to be there.

Any of those things you listed in the OP could make batman snap and kill him, the difference is that it would have to be immediately after. It would have to he an impulsive, emotionally driven response. He tried to kill joker immediately after he killed 'Tommy Elliot'

This guy has it.

Batman would never do something so cruel through premeditation, it would have to be in a rare instance where he actually loses control - like the Tommy Elliot example above, or (Forever Evil spoiler:) when Lex Luthor "killed" Dick Grayson.

@jayc1324: Hush has to be one of the worst takes on Batman, it's not a real valid source.

He had tons of times and never has killed the Joker.

So there is no reason to believe that is going to change.

Yeah, Gordon just appears out of nowhere to stop him in Hush.

I don’t think Batman will ever kill Joker.