The amphibots are lacking a medium assault unit, sure they have the grizzly but it's not like the ravager is to the rover factory.
So the idea would be unit which has a torso of forwards facing saw blades and a shield that is not spherical but instead an actual shield shape, this special shield would have collision damage, or at least fake damage (if touch shield at 50 "speed" do blah blah blah damage). it would also be equipped with a harpoon- think of it as a projectile with gravity, it his the target and locks an invisible graviton beam onto it.
Remember the saws? They would kill things not killed by the collision from the shield.
Making sure this is not epically over powered; the harpoon would travel at the same speed and projectile arc of a bouys gun.
Also you can go around the shield and kill it from the side or behiend.
Also the shield gets drained if/when something hits it but it is an especially tough one.
