The foulspawn are mutated abominations that appear to be native to the Astral Sea. Seth fought some on the Zephyr, and Zephyrus Raptorr said that other have been attacking settlements after the Puncture. Foulspawn revel in destruction and carnage, much like demons. Unlike demons, however, they occasionally turn their hateful cunning to the service of others, working as mercenaries or forming small bands with distinct power structures.
Many foulspawn can be dealt with only through intimidation or battle. Some, however, may accept bribes for peace and are willing to fight alongside the highest bidder. They feel no loyalty towards those they deal with, however, and are vigilant for opportunities to stab their employers in the back if it means more profit (and carnage) for them.