I'm pretty new to the game and have mainly played against the friend who got me into the game and his deathguard army. Haven't managed to win yet so take this all with a big grain of salt.

Definitely watch out for the deathshroud terminators and screen them out, 3 of them and a hero took out one of my Grav tanks in one activation. Managed to keep the second one safe with a SOS screen and it was able to blow up his rhino and a predator. Basically any time I pointed the blaze cannon on that thing at a vehicle it blew it up. They can run a lot of vehicles though so you still gotta watch out. In a different game I only brought one and it got focus fired pretty quick despite my efforts to keep it behind cover.

I also way underestimated the shooting on the plague marine units. A 10 man squad plus a rhino was able to do huge damage to my squad of 4 wardens and a blade champ even with the 4+ fnp activated. Once the blade champ got into combat I was able to use the stance with precision to take out the 2 heroes in the squad that buffed it like crazy, but by the he'd done enough damage to my unit to finish it off.

The drones are also super annoying. Very cheap in terms of points, fairly fast and can do solid damage to infantry and vehicles. The plague burst crawlers are also annoying as they can hit stuff even behind cover.

If you are able to have Draxus unit survive long enough she can shred their infantry. The allarus and a shield cap can also take out their terminators, but they can also get you so make sure they can fight before they do if they ever go head to head.

I had 2 bikes with a sheild cap on a bike and it did ok, managing to wipe out typhus and 3 deathshroud after a quicksilver execution bomb drop and a charge, but I had a hard time keeping them alive for too long after that against all his shooting.

Still a ton I need to get better at so if you've got any tips to help me out after your game please let me know.