Tome Powder

Tome Powder
Chance of Addiction: 20% per use, cumulative
Cost: 2,500 gp

This intoxicant is manufactured by grinding millennium-old tomes of ancient, forbidden knowledge into dust.  The dust is then sifted until only grains with ancient ink upon them remain, and the resulting powder is snorted.

Effects:
Visions of the far past are revealed
25% chance that a fact from the tome is known (e.g. a new spell, the location of an ancient treasure, or the secret name of a potent extra-dimensional entity)

Addiction:  Addicts suffer from writing appearing on their skins in a long-dead tongue.  This writing will hold secrets desired by wizards and liches, and they will eagerly seek the addict’s skin.  The addict’s skin may likewise be ground into more tome powder, effectively "recycling" the ink.

Withdrawal:  Addicts require more tome powder every seven days.  In the absence of such, they will begin unconsciously reciting any forbidden knowledge that they know – causing potential for accidental summonings and spell-castings.