Well, it does need an area attack, but I'd think it's easier to turn one of it's natural weapons into an area attack, devouring everything in the targeted area at one shot. Earthbound aura seems a little too forced though, and people can still fly above that too.
You'd want attacks to be of decreased effectiveness as range increases, such that to do any real damage, you'd have to be very close, within charge range even. Alternatively, augment the caraspace such that it's even more potent at denying ranged attacks.
You'd also want it to very strongly resist battlefield control. Terrain should be no obstacle, it'd just consume whatever mountains are in the way.