https://keith-baker.com/ic-wildheart/
The Wild Heart embodies mortal fears of the natural world. To some degree, this embodies the sheer unknown that the wild represents, but it especially draws on the fear of predators—the unknown dangers lurking in the depths of the darkest wood. The Wild Heart is known both for its connection to gnolls and as one of the primary sources of lycanthropy; in my Eberron, it was the cause of the Lycanthropic Purge.
As a force fundamentally opposed to civilization,
the Wild Heart uses no name and takes no part in
the schemes of the Lords of Dust. Its speaker is a
shapeshifting fiend known as Drulkalatar Atesh, but its
fiendish minions are more likely to possess or be fused
with beasts than to act in fiendish form.
Source: Chronicles of Eberron