From publisher blurb:
It seems to me that many of us have some sentiment for hordes of orcs, goblins, gnolls and other so-called „wild humanoids”. Sometimes this sentiment comes from Tolkien, sometimes from video games like Icewind Dale – that’s my case – and sometimes simply from the fact that they are classical low-level opponents in many fantasy RPGs.
Hordehearts is a supplement designed to refresh this "evergreen" motive – it provides you with a description of strange creatures that can enter a symbiosis with a wild horde, feeding on members’ emotions and vitality but also protecting and empowering them in return.
To make Hordehearts as easy to use as can be I’ve described only the most basic information on them as facts, leaving numerous possible interpretations where possible.