You have discovered the secret of tapping into the Dark Duality of magic.
Prerequisite: Cha, Int or Wis +18, ability to cast 3rd level spells or hexes.
Benefit: Your magic is now partially powered by the Dark Duality. You can use magic items which draw their power from the Dark Duality without taking damage.
Spells from the Illusion and Necromancy are cast with increased power and efficiency. Add a +1 bonus to the DC for all saving throws of spells you cast from those schools. Spells with the darkness descriptor or the shadow subschool add a +1 to the effective level at which they are cast. These bonuses are cumulative, so that a spell from the Necromancy school that has the darkness descriptor would have both a +1 to saving throw DCs and a +1 to the level it was effectively cast at.
Tapping into the Dark Duality is not without its costs, however. Spells from the schools of Evocation and Transmutation have their effective caster level reduced by one (except spells with the darkness descriptor or from the shadow subschool). The reduced caster level affects the spell’s range, duration, damage, and any other level-dependent variables the spell might have, including dispel checks against you. Spells with the light descriptor are weakened even more; their effective caster level is reduced by two.
Any attempt to identify spells cast by a Adept of the Dark Duality through Spellcraft have their DC increased by +5. Spells and items which automatically identify spells in effect function normally.
Any magic items you craft draw their power partially from the Dark Duality. Anyone attempting to use such items that has not been initiated into the mysteries of the Dark Duality must make a Use Magic Device check (DC 15 + the caster level of the item) or take damage (10 hit points + 1 hit point per caster level of the item). Use in this case is defined as activation for those items which require action, being worn or handled in the case of passive use items such arms and armor as well as rings, clothings, etc.
Special: The mysteries of the Dark Duality come with a price. When this feat is taken, you immediately lose one level. This penalty cannot be removed through the use of restorative magics such as restoration or greater restoration. The only way to remove this penalty is by mastering the power of the Dark Duality (taking the Master of the Dark Duality feat) or surviving passage through the Darkbridge (artifact); which confers the Master of the Dark Duality feat upon survivors.
