Rock Flesh

With Rock Flesh, the Necromancer gets skin as tough as rock, essentially making the caster temporarily invulnerable to any kind of injury. This is an exellent spell to cast before passing a danger zone, having the same effect as a purple potion, however lasting 100 seconds longer than said potion.

Note however, that it only negates injury damage. Heat damage from lava or drowning in water is still very lethal.

Trivia

 * This spell is the only way in the Shrine of the Ancient Ones to pass through the colored beams of death.