Does the spell from the lore of metal, Glittering scales ad more armour to Saurusar or does it not work since they already have 5+ scaly skin?
There is a thread about this question here already. I am sure it used to stack, but if GW have now made 'scaly skin' a rule in the main rulebook, and the rule counts for both our natural one and for the spell, it would be hard to justify stacking them.