The only things I've found that affect the dragon attack are the level of the dragon (I think) and the number of skill levels you have in dragon ability.The non-artifact items I look for first are the rings "of xxx Magic", which boost the effects of the spells in the appropriate school by 50%. After those, I look for items which regenerate either hit points or spell points - or preferably both!
I don't usually bother with the HP and SP boosters except at low character levels. For a cleric or sorcerer with 400+ spell points, an extra 20 or so is unimportant, especially when you're casting spells each of which costs more than that. IMO, if a character's HP &/or SP get down to levels where an extra 25 make a critical difference, it's well past your party's bug-out time.
