The Ironclad

Clad in corroding armor plates, some Champions contain their bodies to prevent guts and rot from spilling all around. They carry armor not just for the sake of protection - layers of rotten flesh and nurgles gift are providing resilience far beyond any conventional armor - but for mobility.  At a certain level of decay, armor becomes less encumbering than carrying none. 

Especially if demonic strength provides power and endurance of unimaginable plenty.