Source: Shards of Sin, pg(s). 82
Fleshdreg are malformed sinspawn created by a malfunctioning runewell. These small lumps of flesh walk to two hideous legs and have mouths full of sharp, jagged teeth. There are minor variations among fleshdreg generated by runewells associated with different sins. Fleshdreg can sense creatures who represent their associated sin.
Fleshdreg require no sustenance, thus they are essentially immortal unless killed in battle. Even though sinspawn treat them poorly, many fleshdreg gather around and follow them.