Part of Yaeth's Compendium Pg. 118 [right side]  

 

Dropped for me from Corrupted Unicorn in Wakening Lands last night.

yaeth's 118 Right dropped off a Master Assain in Up last night while taking out doomshade.

drops in VT off Zun Centien aswell

This drops in Umbral Plains off of Taewro (spelling). He is in the ice tunnel. Can take him down with a very small group and possibly duo him if you have a shaman/tank combo. Tricky part is getting to him, which you probably can't do duo. You really need a monk, tank, shaman combo. Move up tunnel until you get to Swarmcaller. Put invis to undead on monk, have him run past Swarmcaller, he will get aggro (it sees through). Have him hold the Swarmcaller up the tunnel right as it turns to ice. Meanwhile tank and shaman put up invis to undead, and walk past the other mobs in the room with Swarmcaller (do not see through invis to undead). Kill Swarmcaller. Warning, do not kill him in his spawnpoint, you must be past spawnpoint when you kill him because he spawns the Swarmlord when he dies. Swarmlord will kill you. Enough said. For the ice cave part there are four mobs, 2 see through regular invis and invis to undead. Have monk split, take out the see invis ones. Walk past , take left tunnel (I think, check this), and you are at Taewro. You have to kill his ph and then the real mob instantly spawns (like the Swarmlord). He slowable, hits like a girl, quite a lot of hp though so its a long fight.

Also saw one drop from one of the valley dragons, not Sont. Friend said it drops from Ssra as well, but didnt see it firsthand.

Anyone know where a good place to loot one of these is? It's part of the combine for Torpor, and very much sought after.