Iron dragons, like all metal dragons, have very high defence. As with all dragons, an anti-dragon shield or cure potion is essential when fighting them. Without the shield, you can be hit extremely hard by the dragon's firebreath, while Protect from Magic and the cure potion will only provide added protection. It is possible to reduce the damage from the dragon's breath using Protect from Magic, but this effect does not stack with the shield or the potion, and the dragon will still hit over 300 without a miss when it uses its breath.