https://bugs.winehq.org/show_bug.cgi?id=34480
--- Comment #33 from Riccardo c10ud.dev@gmail.com --- Workaround for League of Legends:
add x3d_platform=1 to [General] section of Config/game.cfg
This undocumented setting enables OpenGL rendering (0 is d3d, 2 should be sw)
hope it helps (original issue stands)