From Pathfinder #195: Heavy is the Crown, which isn't enabled.

Cavern's Heart

ITEM 14

RARE EARTH MAGICAL

Price 4100 gp

Usage etched onto med heavy armor

Bulk —

This armor can channel your life force into an enhanced Wall of Stone.

Activate command

Frequency once per day

Effect By stamping your foot on the ground and calling out to spirits of stone, you summon a stone wall. This is a wall of stone, except that the wall is tied to your own life force. When the stone wall is damaged, you are damaged instead. If you are reduced to 0 HP, the wall is destroyed. The effect is dismissed if you move more than 30 feet away from the stone wall or if you spend a single action with the concentrate trait.

Pathfinder #195: Heavy is the CrownOGL