Punishing Radiance

Epic Tier
Prerequisite: 21st level, any divine class
Benefit: Whenever you score a critical hit with a divine attack power that has the radiant keyword, the target and each enemy within 5 squares of it gain vulnerable 10 radiant (or its existing vulnerability to radiant damage increases by 10) until the end of your next turn.

Published in Divine Power, page(s) 142.