Since v77 Bromite uses Chromium subresource filter with the full filter lists mentioned in the README.

This engine does not currently support CSS rules; as a result some sites will show ads.

The Bromite AdBlock Update Service checks at startup (after 5 seconds) and periodically (every week) if new Bromite filters are published; if no new filters are available (checked via Last-Modified header) then update is skipped.

Filters are downloaded from https://www.bromite.org/filters/ and they are published via https://github.com/bromite/filters

You can use your own custom filters, see https://www.bromite.org/custom-filters

The ad-blocking engine of Bromite till v76 was an improved version of the original engine of NoChromo, which is a very simple ad-blocking engine if compared to the others available.