Select the parent folder that contains the exefs components. Do not target the specific .ips patch file itself, as the emulator requires the folder tree to register the hook properly. Launch the game.
D2R expects specific files for online play. When a mod alters these files, the game prevents launching to avoid corruption.
Disclaimer: This article is for educational purposes regarding game file modification for offline single-player use. Modifying online game files violates Blizzard’s EULA. The author assumes no responsibility for account restrictions if you connect to Battle.net with modified files.