Shared Madness is a 1st level avenger Encounter power that was introduced in the Player's Handbook 2.
The wrath of your god sears the mind of one foe and echoes to assault another enemy as well.
Encounter ✦ divine, implement, psychic
Standard Action
Ranged 10
Target: One creature
Attack: Wisdom Vs. Will
Hit: 1d10 + Wisdom modifier psychic damage, and a second creature you can see takes the same damage.