Kharn make its to round 5. He's definitely not getting taken down by blunt trauma if a multi-hundred tonner couldn't do it no one here has a hope of beating him down. His healing means that blades are also going to not be as effective as they should be. If getting himself disemboweled didn't phase him nothing short decapitation is going to do him in. I'll say he stops at Scarlet Spider. Scarlet Spider's speed and his tendency to go for neck snaps straight off the mark leans it toward him.
What exactly are we calling "Peak" for the Death Guard? If this is the DG before the loss of their numbers but post Heresy with the Deamon Primarch Mortarion, Typhus and his destoryer hive and all those Deamons that Mortarion was pumping out like a gooden. I'm thinking the DG have serious chance at wining here.