Living Armor (Attuned), Rare (Requires Attunement)
A translucent carapace-cloak that settles over the shoulders and hardens across the body when danger nears. It is worn and attuned — one attunement slot, no bond slot, no Communion, no Infestation — and thickens as its bearer grows. Its benefits apply only while you wear no other armor.
Nascent (1st Level). Your base Armor Class is 12 + your Dexterity modifier.
Hardened (5th Level). Your base Armor Class becomes 13 + your Dexterity modifier. When you take damage, you can use your Reaction to bloom a plate of shell and gain 5 Temporary Hit Points. Once used, this can't be used again until you finish a Short or Long Rest.
Chitinous (11th Level). The Reaction now grants 10 Temporary Hit Points, and while you have any of those Temporary Hit Points you have Resistance to the triggering damage's type until the start of your next turn.
Source: Sporebound