Rank 3: Leman Russ (Space Wolves)
Among the Primarchs, Leman Russ is regarded as one of the best, but certainly as the wildest warrior. His Space Wolves are inspired by the myths of the Vikings, and Russ himself often fights like a berserker.
Physically, he is not on par with Primarchs like Vulkan, but he has had to fight for survival literally since childhood. He grew up as a fighter on an icy world, training to develop his ferocity and toughness.
His wildness is the reason some accuse him of nearly destroying the Imperium. However, he is not blindly bloodthirsty but rather a skilled fighter who studies his opponent in a duel and systematically exploits their weaknesses.
In battle, especially against other Primarchs, Russ has the advantage of a special technique. He can emit a wolf howl that psionics find so intense that their ears may bleed. So, psionic tricks help little against him. Much like Rogal Dorn, a battle tank of the Imperium is also named after Leman Russ.