Can we have more context please? It often means you are about to succeed in a big way, often at somebody else's expense (you will succeed, someone else will suffer). Usually we say, In for THE kill. There is a song by that title, I believe. An English group called La Roux sang it. Got to Number Two in the charts, I hear. If you are in business you can 'go in for the kill.' It suggests you are about to make a final move, perhaps in a takeover bid. In the animal world, and the world of human hunters, we literally 'go in for the kill.' We move in and kill the prey. It could apply to any situation where we finish off an argument or make a final move to triumph over someone or something. We also make 'a kill' and 'a killing. For example, you can make a killing on the stock market - which means you make a lot of money. These are just some examples of a commonly used phrase. Other people will suggest other uses, I'm sure!

I agree with MoiraWendy. The correct expression is 'Go in for the kill' or 'Move in for the kill' Here's a definition : :to prepare to defeat someone in an argument or competition when that person is already in a weak position (http://dictionary.cambridge.org/dictionary/british/move-go-in-for-the-kill) If you imagine an animal preparing to kill another one: first it weakens its enemy, and then it makes a final deadly move that will finish it off. That's what 'go in for the kill' means. We might use it in a chess game, for example, when one opponent is about to make his final moves to win the game.

it means u will die soon whatever.

It can mean like you messed up, you're going to die, or it can literally mean you're in to kill someone lol