Most armies have their dedicated elite infantry, and from the Freeguild Greatswords to the Kharadron Grundstock Thunderers they bear an infamous reputation on the battlefield. Each of the Skaven Clans have their own as well, and those fielded by the Clans Pestilens are known as Plague Censer Bearers.
The standout strengths of the Censer Bearers are evident. Unlike Plague Monks their weapon range is 2 inches, meaning they can actually swing over the top of themselves when taken in large groups. Their base rend on their weapons is -1, above the Plague Monks who need wound rolls of 6 to compete with that. Topping this off, in the hero phase each unit near them has a chance to take a mortal wound on the side. They also reroll all failed hits and battleshock outcomes as long as they hang close to a unit of Plague Monks, which in any smart list they'll have at least 2 or 3 units nearby.
No save, and unlike Plague Monks, no way of acquiring one. Furthermore, they're 60pts for 5 models, and that's 60pts that can be erased by merely average shooting. This is an elite unit that cannot withstand ANY level of pressure, so they need a stack of buffs to hit their full potential.
With the Verminlord Corruptor's command ability, the Plague Furnace's Rabid Fever and Bless with Filth, and maybe an enemy debuffed with Wither for good measure, these guys will literally EAT anything they go up against. A unit of 10 swinging for 40 attacks rerolling all of it's failed hit and wound rolls is going to blitz ANYTHING short of a 2+ save rerolling fails. Taken in the Plaguesmog Congregation they will be -1 to hit with shooting and putting out far more proximity mortal wounds in the hero phase. However without these buffs, they'll get swatted turn 1 or 2 and you'll lose your high cost point sink. Take them in a group of 10 and a group of 5 as part of a Plaguesmog for the extra artifact and command point or don't take them at all.