Holy Symbol Expertise

Benefit: You gain a +1 feat bonus to implement attack rolls that you make with a holy symbol. This bonus increases to +2 at 11th level and +3 at 21st level.
    When you attack an enemy with an implement attack using a holy symbol, your enemies cannot gain combat advantage against you until the start of your next turn, unless you use a power or another ability that states that you grant combat advantage.

Published in Heroes of Shadow, page(s) 157, Class Compendium.