[Firestormalpha]

For dragons you want to protect against the damage type they do. not magical or normal weapons. At least that's my guess. Say for example Big Red, you want protection against fire. Stack as much of it as you can and let the bad boys fire breath heal you if you've got enough. As for protection from the physical attacks get your AC as low as you can. I've had mine as low as -12, but can't recall how quickly in the game I was able to do that.

However, it would help if we knew what kind of party/characters you had to work with. At what levels, or you could just check out SixofSpades website with lots of cool info.
Here's the link: SoS's BG Guide