You exert your will over the stuff of shadow and conceal an ally in pure darkness. No light reveals your friend now.

Encounter   ✦     Arcane, Illusion, Shadow
Standard Action      Close burst 5

Target: One ally in the burst

Effect: The target becomes invisible until he or she attacks, or until the end of your next turn.

Published in Forgotten Realms Player's Guide, page(s) 67.