Vana'diel Bestiary: Lost Soul (BLM)  

If you are doing the DRG AF1 NM fight (Decurio I-III) with a party of sub-50s make sure you aren't fighting it at night. The area around the ??? spot where he spawns is home to a couple of spawn points for these nuisances. The BLM variety will definitely mess up your fight as they will Silence everyone. We had 2 aggro on us, one of each kind. Our WHM got silenced and our Tank had to deal with the combined attacks of Decurio AND the WAR Lost Soul. If you have to fight it at night, just make sure to sweep the area for any of these guys (as well as extra Anticans). Otherwise you may end up regretting it.