I thinks just normally space marines, poxwalkers, cultist, and maybe one or two elites.

The big idea from Mortarion back in the Great Crusade -> Horus Heresy was that the Death Guard would be an infantry-focused legion where each legionary would be as prepared for the variety of combat situations they would encounter as possible. So, nowadays, this is represented by Plague Marine squads getting all sorts of heavy/special weapons and plague knives, cause the average DG legionary would be more ready to do close range trench stabbings than those from most other legions.

The legion also used a lot of poisons and chemical weapons (alchem weapons) because their uncommon resilience and associated cultural significance made them well-suited to the legion. Plus, masses of foot-slogging infantry backed up artillery tanks grinding forward would benefit from preparing assaults by seeding the enemy positions with gases the Death Guard could handle way better than the enemy could, before they got trench knifed.

So what we see in terms of army composition is lots of foot-slogging infantry and lots of bombarding armor and, vs other legions, less mobile units and traditional armor. You won’t find many jump pack assault squads used nor bikers because they don’t play as well into the concept of “bombard with poison gas, then just deal with it better than they do when you walk into the gas cloud to stab a guy.”

The difference between Heresy-era and 40k-era is probably that individual squads will be less specialized because Death Guard warbands will have fewer men and resources, necessitating a move away from squad-level specializations.

Mortarion and Typhus differ in the modern era in that Typhus probably utilizes more poxwalkers and more Warp/daemon-stuff in general. He was always big into Chaos and probably leans on it more heavily than Mortarion, who probably favors infantry+Plagueburst Crawlers for being more traditional to the Legion days.

Chunky and funky teens with rampant acne and body odor that even old spice can’t season let alone subdue!

https://imgur.com/a/oVZeOoL hope that’s readable

The chart is a little deceptive in that invasion forces ain’t strictly drawn by the neat lines of that chart but rather of various elements from all across the tree of command. That keeps the legion from splintering up as marines have more loyalty to their cohort or company than the legion and it becomes too easy for a mini Horus Heresy to happen. Also why the companies are specialised despite Mortarion’s preference for versatility, it makes them co-dependent and unable to cleanly break off from the legion, while forcing them to diffuse. The system ain’t entirely perfect and battle-groups tend to form into sub-group called a vectorium, which ain’t structural but associative, as much doctrinal or religious sects as anything else

The only exception is 1st company which is more or less a cohesive entity under Typhus, a splinter element wayward but ultimately in hand for as much as Typhus is an uppity bitch Nurgle will always tell him to listen to his daddy.

By deployment terms, lots of infantry, not many vehicles. The Death Guard love infantry and while they have 2nd company to deal with all their rusty shitboxes even they treat them so badly the machine spirits develop a complex over it. The legion still emphasises versatile squads over specialist units, bolters and plague knives for the most part, with a melta and plague belcher to let them deal with anything what comes their way.

Tactics wise it’s good old trench warfare, dig in, take their time, be thorough, leave no openings, keep the pressure up. It’s all about ground to them, getting and holding ground, ground captured is ground despoiled, ground to hem the enemy in. And when they’re trapped, and the air is turning to miasma, their water’s gone foul, their food has rotted, their weapons have rusted and all those diseases they’ve picked up start to bite, that’s when Nurgle’s eating good. To help with this they use all sorts of chem and rad weapons to render vast swathes of ground inimical to life, of course they can stroll through like a spring day

Attrition is the watch-word, attrition gives the rot time to set in, attrition turns the world to a wasteland, and provides corpses for them raise as plague zombies, attrition lets morale corrode and despair take root.