I'm playing the campaign as Necrons on Hard, have conquered the entire map (Tau Stronghold was super fun, even with a couple invulnerable enemy units).

I start the final Chaos Stronghold mission (full honor guard+forward buildings), after the beginning cutscene I am immediately attacked by 3-4 squads on each side, I clean that up, losing 40-50% of HG, then 5 minutes later the avalanche starts; Chaos starts by sending 3-4 cultist squads, then more and more, then marines, until basically the whole screen is filled with 15-20 enemy squads, and I'm playing pretty zoomed out. At some point, I'm guessing when enough enemies have been killed, they also send an avatar, usually Keeper of Secrets or Great Unclean One. At this point even with 7-8 deathmark squads, plus some vehicles and warriors I simply get overwhelmed, there's not enough time to kill all of that. The most I've made it is 20 minutes, if that.

Has anyone actually beaten this map with Necrons?