Improved Magic Warding (Stronghold Augmentation)

Magic Warding: When creating this augmentation, choose one face of the wall. Anyone within 5 feet of the chosen side of the wall (including those standing atop the wall) gains spell resistance 32 or against any spells cast from the other side of the wall. If the caster’s line of sight to a target does not pass through the plane of the wall, the spell is unaffected.
Caster Level: 20th; Prerequisites: Craft Wondrous Item, spell resistance; Market Price: 50,000 gp