Subterfuge is very powerful, and compares favorably to similar 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 to use this in an area where there are multiple enemies at one time. While hidden, use the Throw Voice and use Subterfuge when they are in one area.