Terror feind
A mage level 56 would have trouble hitting it with any attack unless he would have some spell on him like Tenser transformation, or a Empowered Empowered Empowered Empowered Empowered bull strength or something like that (AC 50+ or so) Actually, a mage 56, if he didn't have spells would probably get cut diced and served for dinner (remember no fire lightning cold sonic force and almost all undead immunities with a few exceptions)
Anyway, rereading the description of Dimension door, I'm not sure it's even that he used that spell stunned after for the rest of round), perhaps he teleported and with his haste readied an action to right after being telekinesised cast iron body.. I don't remember much of that combat (Repressed memories perhaps ;P)
Also Terror feinds and Deraxes (the most powerful one of the 2, almost on demon lords's power level) was a import from 2nd edition with a little "Tune-up". We had a "Champion of the Gods" called a "Dragoon" (home prestige class for past 20) with us to take those (we could barely with our 20th level group stand against one Terror find on favorable terran (We prepare, ambush and the like). They are the destroyer of universes after all, they must be powerful
Beside that, what are the rules for damage? Does the one being hurled gets the damage too? Damage reduction applies or not (+3 weapon in the case of iron body?)? And last but not least : How much does the different dragon weight?