What is the best Opening for Black against the London System?

Hello, I need a good opening against the somewhat all-powerful London System which can push Black off the board. What is the best defense/offense for black?

I used 'pushed off the board' because Black is running out of playing space. Does black have any powerful weapons against the London System? is what I meant. I can try to take your advice the next few times I play "against" the London.

Been playing chess for quite awhile (a few years- maybe a decade (not quite ). I think I know tactics and checkmates very well. I can beat almost everybody at least once, however, I  do not know endgames too well but some. I have found that I am a very aggressive player who likes to take risks, such as the Nice little Halloween Gambit, 

My idea of a Chess game: Play until your opponent is DESTROYED.

I am an experienced 1. d4  or 1. e4 c5. player and already know most of the basics of openings. i have not gone in depth of tactics study (Maybe once before). Thank you for your help, but I do really want to know if there is a good idea black should have against the London because on lichess.org there is this practitioner who's really good at it can't beat him, but only once I did.

As someone who plays both sides of that opening, I can recommend the King's Indian Defense as a good way of playing against the London. Also, you could consider the Semi-Slav - which I have also had pretty good luck with against the London.

Try 9. Kxd7 Qxd7 10. Bxd6. Black is in a bad position and white is favorable. I think the King's Indian Defense is easily going to lose, but still playable. I will examine the Semi-Slav of which I have never heard of. Instead of 9...Qxdy, I think Bxd7 would be a better choice. Couldn't you agree more?

Scrambled EggsN Bacon appears to have deleted his posts somehow.

You might go for 1.d4 d5 2.Bf4 c5. See here: https://www.chess.com/forum/view/chess-openings/play-the-london-vs-c5#comment-48305930.

Something similar to the Sicilian Defense: Bowdler attack or so I think. Bowdler is a mistake since Bishop may end up being captured. I was successful last game in capturing that Bishop.

Nvm that is the Queen's Gambit. Looks like a powerful tool to break up the pawn chain.

Most London players hate seeing an early c5.  It's up to you how you want to get there.  You could achieve it via benoni, modern defense, or tarrasch type pwn structures. I've had success with all of them.

My preference is from a 1...g6 move order.

Interesting idea.

Best is 1.d4 Nf6 2.Bf4 c5