Map from half-life 1, in theory can be used in pvp.

It should be safe to use online for pvp, though i wont 100% guarantee that, use it online on your own risk!
To get to this map you need to warp to Shrine Entrance bonfire, so you need it to be unlocked before installing this mod.

To install first unpack your game with UXM (https://www.nexusmods.com/sekiro/mods/26) and then place folders from archive into your game directory (where DarkSoulsII.exe is) with replacement.