My son plays Chaos. I'm just starting with Necrons full time. What's
the best tactic against his Land Raider, with 14 armour on three sides
(12 on the back, I think)?

So far, I don't have a Heavy Destroyer. Is that my only/best hope?

Is assault a good option? He also has a Rhino, but I'm only concerned
about the Berserkers that ride in that, not so much the armament on it.

Thanks,
Bill