Perfect Shell

Your shell is more durable and offer a better protections. You gain the following benefits:

• Increase your Strength or Constitution score by 1, to a maximum of 20.
• When you are withdrawn into your shell, you are immune to bludgeoning, piercing and slashing damage that didn't come from an attack.
• When you are falling on creature you deal 1d6 bludgeoning damage per 200 pound you weigh, provided you fall at least 10 feet. For every supplementary 10-foot increment you fall add 1d6 bludgeoning damage (to a maximum of 20d6). If a creature can see you falling on them, they must succeed on a DC 20 Dexterity saving throw or take the damage.