Wording note: Nei is the ancient palman word for power, so you wouldnt say " i saw him invoking a Nei power " in character you would say " i saw him invoking Nei "
Spellcasters from elsewhere have made comments that when using Nei it reminds them of using spells from their native universes, it is suspected that Nei must be what is left of the original magic weave in this distant realm, while techniques (jutsu) are being powered by the a newer weave constructed by the goddess of Chakra since her reconstitution.
To Cast a Nei Power one must make a Ritual Arts check based off Intelligence, if you Possess the Feat Nei Reservoir your Ritual Arts check would operate on your primary Nei stat instead for the purpose of casting Nei, if you are casting regular Ritual Arts it would still require your intelligence score to make the check.
When a character invokes Nei to manifest a power, he must expend and appropriate amount of energy. Once a character has expended all of his Energy he may continue to use powers (but not any Arts), but must expend wound-points instead of Energy in order to produce them, wounds taken in this way are considered subdual damage. If the supernatural class using Powers is reduced to 0 or less wounds in this way, he loses consciousness and his maximum hit points are permanently lowered by 2.
Nei abilities are not affected by anti energy or Anti Psionic (antiforce) fields of any sort - a lower form of power cannot disrupt a higher form of power, all spells and abilities used by Deities are considered Nei even if they are originally a lower form of power.