Flameproof

Flameproof (or Resist Fire) is a runic spell that appears in Ultima Underworld I and II.

Spell Description
This spell renders its caster immune to all forms of fire based damage, be they magical or mundane. So long as this enchantment is in effect, its user need not fear magical fireballs, and may even walk across molten lava unscathed. Of course, the danger is that the spell can run out at the worst possible moment. There also are items and potions that can fulfill the same function.

Trivia

 * In Ultima Underworld I, Dragonskin Boots are available which allow their wearer to walk safely across lava, although they do not convey the other benefits of Resist Fire. In Ultima Underworld II, however, an artifact known as the Leather Vest of Flameproof allows its wearer to experience all of the protections of this spell.
 * In Ultima Underworld II, purple potions of Flameproof may be acquired throughout the game. The Killorn merchant, Merzan, will also concoct such elixirs for a price, although he will require ten bottles of water in addition to his payment in gold.