This dropped off 'a slithering corathus' in Corathus Creep that turned into a treant but kept the original name.
I got Blood-infused soil in The Bloodfields (level 55 hotzone) and this in Corathus Creep (level 50 hotzone) off mobs that turned into a treant similar to the Cliknar Scouts from a couple hotzones ago. I'm thinking there is 2 more drops that go into this box. Need more info on other drops though.