Magnus has really become the master at this. If you look at his best classical or rapid wins (as in most interesting or novel) of the last few years, they often follow a similar pattern:

- pick a playable but rare line in a solid opening - go out of book early - just scrape through the middle game with often questionable moves - later, sacrifice material for positional/ strategic advantages - rely on his greater 'pure' chess genius to close it out.

The idea is to avoid deeeply studied "safe" lines where it's possible the opponenet has deeper knowledge and then be slightly less off-balance than your opponent throughout. This is all in deep contrast to how the GMs played before Deep Blue where it was all deeply conservative well studied lines. I strongly suspect Magnus, who is known to have an incredible memory for games, keeps a mental database of these obscure lines and plays them only once!