The Drowned Thrall is an Eldritch/Unholy type that appears in the Cove. Sometimes the Fishfolk will seek out humans for their own devilish ends. This poor creature was drowned and then reanimated to act as a soldier against those who foolishly trespass into the domain of the aquatic devils.
The Thrall will use both of its abilities in a row. The first, Gargling Grab, does serious damage while also causing stress. The second, The Revenge, will cause it to self-destruct, dealing massive damage to your entire team. It is very weak, though, so it will be easy to kill before it can decimate your party.