Self-Sealing

A suit of armor etched with this rune can create a bolstering magical layer that closes off to protect the wearer against dangerous environments. When you would take environmental damage, or when you enter an environment where you can't safely breathe, your self-sealing armor seals itself shut. It holds 1 minute's worth of air and grants you resistance 10 to environmental damage while sealed. You or another creature can take an Interact action to unseal it at any time. Once unsealed, the armor can't seal itself again for 1 hour.