Change the element. Gravity is known for not having problems with shield. I know your idea is probably to momentum this guy, but the fragile ability doesn't quite fit. Also: why does a fragile creature die from hitting a shield, as what about shields with miss rates (dusk, fog, dimensional) would they make your creature break and if so that really doesn't make sense. I would suggest changing to water element and having the creature act as if frozen at all times (still gets to attack, but gains the extra damage by use of catapult and can break by shockwave)