We killed both of them a ton, but they just didn't have much to offer in terms of drops. Uraeus Skin was about it for Tricorns, but Mosshorn just wasn't worth doing much since he just dropped the horns for that scale mail that wasn't even any good. Both I think were overcamped on the fist day as well, and I can't remember if we got them or not on the day they were implemented in. Someone else in the FC might remember, but I can't lol