Varius

So rotten even his mouth fell off in protest.

Varius serves as Eliphas' personal bodyguard (Though why he would need one is kinda empty) and resident Plague Champion in Retribution, therefore meaning that he's gonna smell worse than fuck-all because he serves an even worse-smelling fuck. It's probably a good thing he doesn't really speak, 'cause his breath would probably kill everyone; not like he could do so since his lower jaw seems to have rotted off. He also serves as the medic for the lot of heretics, using a plague to heal wounds using some sick cancerous growths. He can also use this same plague to also rot away opposition about as quick as the common flamer and, with the proper boost, can also parasitize on his plague, sucking vitality from his dying foes/recuperating allies.

He also gains another nasty trick as you advance down the energy tree: The ability to raise the dead as plague zombies. This skill's very capable of making things hectic, especially since they explode when they die. If you decide to make Eliphas Khornate and raise Khorne shrines, you get an endless stream of bloodletters that fuck shit up, die, get reborn, fuck shit up even more, and then explode, suppressing enemies and healing allies. On the whole, if you go troops-heavy with chaos, it's a must-get. However, if you're on the hardest difficulty where troops are more of a distraction to buy time for the more flamboyant ability animations than they are actual assets, his best spell is by far Accelerate Metabolism, which lets him remove the plague buff from all affected units to do massive healing or damage to them. This can one-shot most hordes and other chaff, although it suffers the crippling disadvantage of hitting only one unit at a time until you unlock plague grenades.

On the downside, while Eliphas, Kain and Neroth can all have some special expertise with certain weapons, Varius is kind of an odd child out, able to use his default bile-spewer, Chainaxes, bolters, Power Swords, Power Fists, and rocket launchers, but not really getting anything to really benefit any of those styles. Preferably, he should be at least distanced enough to allow his abilities to be used without interruption, although late in the game he can be made a decent melee fighter with some of the mission reward weapons and armor, since he's the second-tankiest character (Eliphas has better health regen by a mile).