I own a copy of Ascension on Steam and happened to get the Dark World expansion free on the Epic store (still planning to buy on GOG).
I couldn't find a straightforward way of getting mods onto my Epic store copy so I downloaded the mods for Steam and found and copied the .tower files over to the Epic version.

Is this really the only way to get mods on non-Steam versions? I've tried some of the websites that allow you to download Steam Workshop content, but it doesn't appear to be a reliable solution. Seems strange that user generated content would be gated behind Steam Workshop in this way.