Honestly, about an 8. Last time the crabs showed up, a lot of Rebels died and it shot Sevari so hard it made him want to go home.

Edit: For size reference the crab is about 12ft in height, a bigger version of this thing: [img]http://img2.wikia.nocookie.net/__cb20130210000215/elderscrolls/images/3/3c/Dwarven_Ballista.png[/img]

except with arms with guns on them with claws big enough to snatch a man and crush the life out of him.