Can be tamed.
Located in Ardenweald. Shadow Croaker appears randomly at one of at least eight possible locations around the edge of Ardenweald. See this map for known locations, but there are probably more we haven't found yet. It is initially stealthed and very hard to see, but it can be detected on your minimap if you have Track Hidden enabled. If you get too close it will run away and move to a different location. You need to approach just close enough to use a Freezing Trap on it, then tame away!