Nightingale Subterfuge is a skill awarded to the Dragonborn by Nocturnal in the final Thieves Guild quest Darkness Returns. Stepping on the Half Moon platform confers this skill. The skill is listed under the Powers menu.
People and creatures in the spell's area of effect will attack anyone nearby for 30 seconds. Powers can only be used once a day.
Subterfuge is a very powerful ability, and compares favorably to analog illusion spells. It affects NPCs who are too powerful for Rout — which, even after all perks and a 25% boost to Illusion from vampirism, can only affect NPCs at level 32 or below. Subterfuge, however, will affect most NPCs in the game.
A good strategy is using this in an area where there are multiple enemies at one time. While hidden, use the Throw Voice and use the subterfuge when they are in one area.