Taken from GOG forum. Not my work only uploaded.

https://www.gog.com/forum/pillars_of_eternity/linux_unofficial_patches/page1

So now for the patching method:

1. download the .lrz file for your game version
2. open a terminal in the directory containing the .lrz archive
3. uncompress it via the following command:

lrunzip poe-linux-patch_1.0.0.1_1.1.0.2.delta.lrz 4. patch your game via the following command:

rdiffdir patch /some/path/to/Pillars of Eternity/game poe-linux-patch_1.0.0.1_1.1.0.2.delta 5. just wait a little while for the magic to happen, when your prompt comes back, your game is patched ;)