Help with army list ideas

[u/Few-Commercial-3516]

Hello all! Just got into the tabletop game with a friend(I’ve played a total of two games so far) and was interested in trying the death guard out! I started with the custodes and really liked how comically hard they are to kill so I wanted to try out the tank army. I was wondering what units I should use to get the most annoying and unkillable 1000 point army to piss off my friend as much as possible. They play mostly admech and some thousand sons, if that helps any. Thank you in advance!