Sominae

The Sosarian divine spell Sominae is very essential during dungeon exploration.

Spell Description
The darkness of the evil depths makes exploration next to impossible without a lightsource. While torches are one solution to this problem, this spell enables the caster to have light without having to carry the lightsource around. This saves space in the backpack and frees the hands for weapons and shields. Unlike the lesser Luminae spell, this one lasts far longer, before a recast is needed.

Note that the arcane counterpart to this spell is Dag Lorum.

Trivia

 * Unlike the lesser light spells, this one is actually useful, though torches are still more economical.