From Elemental Lords of Porphyra

Retaliation Subdomain
Associated Domain: Protection
Replacement Power: The following granted power replaces the aura of protection power of the Protection domain.

Aura of Retaliation (Su): At 8th level, you can emit a 30-foot aura of retaliation, lowering your enemies’ resistance to your righteous attacks. All enemies within this aura suffer a -1 penalty to AC, and have their resistance to the elements reduced by 5 (acid, cold, electricity and fire)

Replacement Domain Spells: 2nd – retribution, 4th -greater retribution, 6th – unwilling shield