Travelers from the surface world to the Underdark should plan their trip carefully. Torches, lanterns, or magical light sources are almost certainly a necessity for those who lack darkvision, for though natural light sources, travelers shouldn’t count on them.
Though natives to the Underdark can tolerate the water from stagnate pools and can survive on the fungi that grow underground (at least as a supplement when meat is lacking), much of that may prove to be poisonous to visitors untrained in assessing what is safe to eat or drink. Adventures must generally bring their own food and water if they are not traveling with druids or rangers who have specialized training of the ways of the Underdark.
In general, adventurers will find their skills and abilities operate the same as on the surface world except when noted. Some spells like commune with nature have a different range when cast underground, while others like call lightning that do not work when the caster is indoors also won’t work when underground. Most spells will operate in the Underdark normally unless the spell description notes otherwise.
