This mob is an animal, and charmable by a druid. Very high MR on it though, so dont expect to actually be of much use with it without malosinia or some debuffs. A 350 hitting SK in WL had a nice sound to it though...
The corrupteds in this zone seem to be random spawns, with no PH or apparent spawn timer. Killed this mob last night with a single group, composed of 59 Ran, 59 Pal, 57 Wiz, 60 Shm, 61 Wiz, 61 Dru. Was a pretty tough fight. The Unicorn will Harmtouch for 1001. He also casts fear and blinds (Darkness), in addition to several Dots he will stack on you.
Was tracking some Tigeraptors for the Ice Forged Shackle quest for my Paladin and my Druid ran into this and aggro'd it before my Pally could get him to take the hits, he HT'd my 39 druid for 1001, pretty much killed him with that and a a couple of hits, then turned on my 52 Paladin, luckily I was sow'd and ran far away and camped to clear the aggro. Very mean bugger...