LP approves! Now, to make a counterpart...
Major Artifact (Red Fel)
For all the good that exists in the multiverse, so to must exist as much evil. When the deity known as Fel learned of the existence of the artifact Heaven's Wrath, he realized that to combat such a powerful force of Good, an equally powerful force of Evil must be created. But not just anything would do. No, for this new artifact had to be as subtle and cunning as Heaven's Wrath was direct and forceful.
So, gathering his vast stores of knowledge and power, Fel crafted a tome of utter darkness, known today as the Fell Tome. Heavy, thick, and bound in living skin, the Fell Tome is a force of such pure, concentrated Evil that even the very light of day shuns the existence of such a horrid artifact.
The Fell Tome is always surrounded my shadowy or darker light conditions within 30 feet of it, and no amount of light (magical or otherwise) can penetrate this shadowy aura. Any Good-aligned creature within this aura becomes nauseated for as long as they remain within the aura, though a successful Fortitude save (all save DCs are equal to 10+1/2 the wielder's HD+their Cha modifier, or 20 if it is not currently being wielded) reduces this to sickened.
Despite the darkness, any character that opens the tome find pages covered in a strange language, which require a Decipher Script check (DC 25) to understand. Any Evil being may spend one uniterrupted week reading these pages to gain the power within them. To finish gaining this power, the potential wielder must enact a ritual, using up 100,000 GP worth of unholy oils and other such materials and 100 X the character's level worth of XP.
Should a wielder successfully bond to the Tome, they gain a +2 profane bonus to all their mental ability scores for as long as they remain bonded to it, as well as a +5 per 5 HD (minimum +5) profane bonus to all Knowledge checks, which are considered trained skills as long as the wielder is bonded. They may hide any physical characteristics taken on by them through Vile feats such as Willing Defomity when they are not being used, and they may supress the dark aura of the artifact itself. Any Good creature within 30 ft of the wielder takes a -1 profane penalty per two character levels (minimum -2) on all d20 rolls, as well as any damage rolls. (This overlaps - doesn't stack - with any penalties from the sickened/nauseated conditions caused by the artifact.)
The wielder may use Unholy Aura, Blasphemy, and Destruction as spell-like abilities 3 times per day, and Morality Undone as a spell-like ability at will (but no more than once per round). They may also summon wings of darkness as a supernatural ability that gives them a flight speed equal to twice their base land speed, with perfect maneuverability. As a standard action once per day, these wings can also give off a mist of overwhelming darkness, causing any creature within a 60-foot radius of the character to become confused, as per the Insanity spell, unless they succeed on a Will save or are purposefully excluded from this by the wielder. The wings may be dismissed as a free action.
However, the most powerful aspect of this artifact is best used by prepared spellcasters. Any prepared spellcaster who wields this artifact may prepare any Corrupt spell of any level they have access to, as each of these spells are contained within the pages of the Tome. In addition, prepared spellcasters who use spellbooks (or similar methods, such as an Archivist's prayerbook) may use the Tome to contain their spells. They may inscribe their spells in the Tome without paying the GP cost per page, and there is no limit to how many spells can be inscribed - there always seems to be enough pages. Spells inscribed this way are only usable by the one who inscribed them. If the wielder takes one point of Con damage (per spell) upon inscribing any of these spells, they may add +1 to the DC and effective caster level per 4 HD to these spells whenever they cast it, and these spells gain the [Evil] descriptor.
Finally, once per month, the wielder of the Fell Tome may use Mindrape as a spell-like ability, except it will not allow any saving throw, and only works on Good creatures. However, there is a catch - you cannot cause any permanent changes to a creature's psyche this way. It may be used to implant certain contingent urges and orders within the victim, set to trigger under certain circumstances.
Any Good creature who willingly comes into contact with the Fell Tome gains one negative level for each round they remain in contact with it. After 24 hours of possessing these negative levels, the creature must make a Fortitude save for each or lose one character level (or Hit Dice) for each failed removal. These negative levels can effect creatures immune to negative levels normally, but they don't risk permanent level loss from these. In addition, any creature with the [Good] subtype that attempts to willingly come into contact with it must make a Fortitude save or be instantly destroyed, as if through a Disintegrate spell. A successful save negates this effect, though they are still subject to the negative levels.