One gap for the Death Guard is a lack of long-range firepower. So the obvious solution was to sort out a supporting detachment of Havocs and, when Shadowspear dropped, Obliterators and a Venomcrawler seemed like a good way to complete a Spearhead Detachment.
I wanted to keep an entirely Nurgle-aligned army so, despite the temptation of Slaaneshi shooting-twice stratagems, I chose to paint these guys up as The Purge (partly because their trait of rerolling hits once a target has been wounded is pretty good too).