Something to throw down that can’t be shot through from either side. This is directly aimed at preventing kraken from body camping from the air with his standard attack.
Another one I thought would be interesting is a support who could block of entrances and exits. I haven’t taken the time to think if every map has an area this is useful not. An example would be a monster goes into a cave and you go around to the exit and throw up a temporary wall (unknown) time or damage before it disappears. It would look similar to a force field like the one mentioned above. Can be used to make a monster turn around or even block off an entrance to an area.