This is a drug I came up with for Joop van Ooms to be addicted to in Lamentations of the Fallen Lords. It's based heavily on the Purple Lotus Powder from Death Frost Doom and the various flavors of Lotus Powder from Carcosa.
This is a widely-abused/enjoyed drug in the Free Cities of the North. Effects last 3d20 minutes. Three or more doses in a human (or demihuman) body at a time causes an overdose - a character who overdoses loses one point from a random ability score, falls into a coma for 1d12 hours, and must make a Save vs. Poison or take 1d10 damage.
Yellow Lotus Powder is quite illegal. This doesn't stop much of anybody. The base price of a dose on the black market is 25 sp.
Users experience a very pleasant buzz/tingling sensation for the duration of the drug's effects. In addition, the user must roll once on the following d30 table per dose:
1. Sensation of extra, phantom limbs, generally where limbs don't belong
2. Slowed (as the spell Slow), plus color blindness
3. Extreme loss of balance
4. Hasted (as the spell Haste), plus tetrachromacy
5. Extra-strong sense of smell
6. Ability to either Speak with Animals (as the spell, 50% chance) or Speak with Plants (as the spell, 50% chance), but with the added delusion that they can do both
7. Ability to sense all multi-cellular life within 300 feet
8. Infrared vision
9. Ability to Detect Magic (as the spell), plus somatosensory amplification
10. Become warm - overwhelming desire to remove clothing
11. Everything tastes like candy
12. Contact Outer Sphere - ask 1d4 questions and get answers that are at least mostly true
14. Contact Inner Sphere - ask 1d4 questions and get answers that are lies
15. Exploding Head Syndrome
16. Strange appetites
18. Strange lusts
19. Obsession with a particular number or numerology in general
20. Believe self to be invisible
21. Ability to detect whether or not someone is intentionally lying
22. Charmed by everyone who speaks to them (as the spell Charm Person, without the HD limit)
23. Cotard's Syndrome combined with the inability to feel pain or temperature
24. Acts drunk, suffers amnesia regarding the duration of this effect afterward
25. Hallucinates, but gains 1d4 skill points for the duration of this effect
26. Absolutely believes the next three things heard
27. Fully rested, as if having just slept for 8 hours (This lasts beyond the effects of the dose, for the normal amount of time it takes to become tired again.)
28. Incredible self-esteem
29. Hallucinates, but gains 1d100 experience points (This lasts beyond the effects of the dose.)
30. Hallucinates, but gains 1d4 points of Intelligence, Wisdom, and Charisma for the duration of this effect
With every fourth dose taken, the user must make a Save vs. Poison or become addicted. It does not matter how much time passes between doses - every fourth dose calls for a saving throw. Addicts require one dose per week or else they lose one point of Constitution. Addiction can be cured with the Cure Disease spell or with 2d4 straight weeks of going cold turkey - falling off the wagon eliminates 1d6 weeks of progress. Curing the addiction does not restore lost Constitution.
Overall, pretty minor stuff compared to most Lotus Powder. This is why it's so widely used and abused. It's mostly used as a party drug or a method of combating boredom, but sometimes people get a genuinely useful random effect and exploit it for a quick burst of creativity or productivity. Sometimes mercenaries who like to gamble or have a death wish will go into battle high on the stuff. Joop van Ooms is currently growing a big batch in his greenhouse for personal use and the occasional gift.