pf2e.fyi
From Pathfinder Lost Omens Ancestry Guide, which isn't enabled.

Fortify Shield

FEAT 5
OREAD
Activity 1 action
Prerequisites Shield Block
Frequency once per day

You reinforce your shield with a rocky outgrowth of metal and stone. You Raise your Shield. If you use the Shield Block reaction before your next turn, add your character level to your shield's Hardness when determining how much damage is blocked.

Pathfinder Lost Omens Ancestry GuideOGL