Myphitic Blight-Hauler
The Myphitic Blight-Hauler is only known for two things. The first is that it is yet another Daemon Engine of Nurgle from the new Death Guard codex. The second is that it the cutest motherfucking daemon engine to have ever exist. Seriously look at this thing! It is like a Chaos Roomba come to life. Look at those stubby little feet, doesn't that make you just go "Dawww"? Only in Papa Nurgle's lair is it possible to have such a collection of adorable little monstrosities.
The Blight-Hauler is a small little fighter that acts as both as a portable gun battery and a light mobile artillery. Appearance wise, it looks much like Foetid Bloat-drone on land. Except, instead of a duct exhaust fan for hover and limited flight, it has three caterpillar tracks that resembles like the aforementioned stunty looking feet. In a sense, the Blight-Hauler can switch to a fire support weapons platform to help assist fellow Death Guard allies thanks to its Bile Spurt which is an Assault D3 Plague Weapon, or it can turn into a dedicated anti-tank platform due to the presence of a Multi-Melta and transform into a make-shift light artillery due to its Missile Launcher. Heck, it is pretty decent as a melee unit due to its Gnashing Maws. All in all, the Blight-Hauler is perhaps one of the most versatile daemon engines in the entirety of the Chaos Space Marines, let alone the Death Guard.
Crunch
For Crunch, what has been said about the Blight-Hauler's weapons and role pretty much applies to the tabletop as well. With the weapons being good all-rounders towards horde armies, armored platoons, close-combat units and entrenched opponents.
Additionally, the relatively small size of the model means that you can have a unit size of 1-3 and if you want them to maximize their capabilities at full size, you could get the Tri-Lobe rule to kick in granting +1 to hit.
It’s also stable and doesn’t suffer the -1 to hit for moving and firing which is a nice match to the Death Guard Legion special rule for infantry. Another special ability is the Putrescent Fog which gives ALL friendly Death Guard within 7" the benefit of a mobile cover when making armor saves, which again mesh nicely with your advancing army of slow moving infantry that would be vulnerable to long range assaults.
There is also the usual Disgustingly Resilient rule will make those 8 wounds last a little longer, while Daemonic and Foul Stench will further extend it’s lifespan. Finally if it does go down, make sure it’s nearby enemy units as it blows sky-high on a 4+, which you can ensure for the low low cost of a single command point.
Tl;dr, It's like a Venomthrope but better.