Snail Mail

Armor (any heavy), rare

This magic armor is crafted from the hardened carapace of a gigantic gastropod. While you re wearing it, you have tremorsense out to a range of 30 feet.

Shell Defense. While you re wearing this armor, you can use an action to cause the armor and yourself along with it to coil into a Small, armored ball that resembles a snail shell. Your arms, legs, and anything you re wearing or carrying are magically withdrawn into this armored ball. While in this form, you gain the following traits:

• You gain a +4 bonus to your AC and can’t benefit from carrying a shield.
• You can’t make attacks or cast spells with somatic components.
• You are blind beyond the radius of your tremorsense.
• As an action, you can roll up to your speed in a straight line. You can move through the space of any creature that is Large or smaller and the first time you enter a creature’s space during this move, that creature must make a Dexterity saving throw (DC 8 + your Strength modifier + your proficiency bonus). On a failed save, the creature falls prone and takes bludgeoning damage equal to 1d10 + your Strength modifier. You remain in this form until you emerge as a bonus action or become incapacitated.