I love the Grell.
So often the Grell is one of those forgotten creatures that lurks about with Flumphs hoping that someone, somewhere, will pull them out and make some use of them.
Not in my campaigns.
In my campaigns the Grell is a masterful hunter stalking the dark places of the world snaring those wizards who believe themselves safe at the back of the line. They kill ponies and horde adventurer treasure like ravens horde reflective bits of trash.
Oh the Grell before all other Aberrations!