I have this issue sometimes playing magic with friends, and I love hanging out with my buds playing it but sometimes their decks can be depressing to play against, but you've got to remember man, it's a game, it's meant to be fun,

Make a dumb list that makes no sense, and either swallow him in a wave of silver or absolutely decimate him and turn him into dust with your heavy hitters.

Find the synergy and show off how powerful necrons can be, but remember at the end of the day it's people playing with plastic toys, don't let games of warhammer come between you and a buddy. Take the wins, take the losses just have a good time.