This page includes an intro and unique info about this beastie. For more info that is relevant to all of the Gloom creatures go to Beasties.
The wolf is a creature of the Gloom. While there's a wolf on your lands you can't do actions around him (including designing actions). In order to banish a Gloom wolf you need to hit him 5 times, each time costs one energy. You can banish a Gloom Wolf by using a Silver Arrow and one energy. Once the wolf is gone you can continue do what ever you like, as long as there are no more beasties on your land.