I'd say play the englund hartlaub charlick, like I do, and punish white for rarely knowing what to do, and to take them out of closed/positional where they want to be and into open & tactical where I want to be, at least.
I bet it's even MORE brutal at the beginner level, but it IS a 2 pawn gambit, so if you're looking for GM approved theory, it might not be for you.
the nice thing about it is it completely bypasses the london after 1.d4 e5 2.Bf4?? exf4! that's what you get for pre-moving! HAHAHAHA!!!
It's the ONLY line I like to play as black. now if i could just get a gambit repertoire against 1.e5, I'd be that much happier.
it's theory intensive, but if you study king's indian, you can have a single system for everything on both sides of the board. you couldn't pay me to play that though because I hate fianchettos
What is the best beginner response to D4? For many people, I find D4 translates to some sort of London system or queen gambit response, but is there a general opening that I could study that would provide a foundational response to white queen pawn opening?