The story goes that the War Hounds decorated their armour with spikes and other such close combat viciousness - this of course went to ridiculous ends when they became the World Eaters!
The Astartes of this Legion often modified their armour by adding large spikes on the shoulder plates to not only evoke fear but also to turn the armour's surface into a weapon in its own right.
War Hounds Appearance - Horus Heresy Book 1 - Betrayal
Now I wouldn't buy them usually, as the Heresy World Eaters don't really appeal, but the torsos will go very nicely with my War Hounds!