Shield Fortification

Prerequisite(s): Shield Focus, Shield Wall
Benefit(s): While you are adjacent to an ally that possesses this feat and is wielding a shield, you grant them [x] fortification.
[x] is equal to 15% while you are wielding a light shield
[x] is equal to 30% while you are wielding a heavy shield
[x] is equal to 60% while you are wielding a tower shield