simple if i shoot a tank with gauss flayers and then roll 6's to glance (gausse rules) do these count as armour hits then?
i know normally a model can only shoot/assault something it has a chance of harming. but in this case the gausse flayer can harm it on a 6 because of its rule. if it was already powerful enough this rule would be pointless because rolling a 6 is a guaranteed penetrate usually.
so am i right when i say i can take down a landraider with a squad of necron warriors?
I haven't seen the new necron rules, but if they're the same as what you describe (same as the old rules) then yes you can. Also just a side note, you can shoot something you can't harm, it's pointless, but you can, you just can't assault (stops you getting an extra 2D6" movement).