How do you kill the dragon in age of origins that is guarding the urn of sacred ashes

I'm not an expert but I'll help as much as possible. Firstly, bring a lot of fire resistance gear and items (such as fire shards and warmth balms) to stave off most of the dragon's fire damage on your tank. Also, a good amount of rock salves (use on your party's tank) would help against the powerful melee attacks. Next, just use your resources wisely, cross your fingers and try your best. If you can't do it the first time, go grind some exp. and then return to finish it off with a more veteran party.