Drug: Devil Weed (Inhaled or Ingested)

Colors seem brighter, laughter comes easily, and time feels stretched thin, as though you were half-walking in a dream.

The dried leaves of the wyssin plant are smoked like tobacco or chewed. After 1d10 minutes (or 1 hour if ingested), you gain the Bewitched condition for 1d4 hours, during which time you experience a sense of euphoria and well-being.

Each additional dose you take while under the Bewitched condition extends its duration by 1 hour. 

Heroic Doses. You must make a DC 13 Constitution saving throw for each additional dose beyond the 5th. On a failed save, you take 3d6 Psychic damage and become Incapacitated for 1 hour. If this Psychic damage reduces you to 0 Hit Points, you fall Unconscious but become Stable. On a successful save, you have the Slowed condition until the Bewitched condition ends, and you may roll one Intelligence ability check with Advantage, ignoring the Poisoned condition for that check. If you roll a natural 20 on one of these saving throws, you immediately gain the benefits of the Contact Other Plane spell. 

Affected creatures: Humanoids, Large or smaller Beasts, Giants, Aberrations and Monstrosities. Fey, Fiends, and Celestials can end the effects at any time as a Bonus Action.

Price on the black market: 10 GP per dose. A typical leather devil weed pouch comes with 5 doses (50 GP).

BEWITCHED [CONDITION]

You are under the effects of Devilweed or a similar psychoactive substance. While you are Bewitched, you feel a sense of well-being and experience the following effects:
Euphoria. When the effect begins, you gain 1d4 Temporary Hit Points.
Vulnerable. You have the Poisoned condition.
Relaxed. You have Advantage on saving throws to avoid or end the Frightened condition.
Skewed Reasoning. You have a +2 bonus to Intelligence ability checks, but you make them with Disadvantage. 

SLOWED [CONDITION]

While you have the Slowed condition, you experience the following effects.
Speed Affected. Your Speed is halved.
Defense Affected. -2 penalty to AC and Dexterity saving throws. 
Limited Actions. On your turns, you can take either an action or a Bonus Action, not both, and you can't take Reactions.
Number of Attacks Affected. If you take the Attack action, you can make only one attack, or one fewer attack if you have the Extra Attack feature or Multiattack.
Falling to 0 Hit Points. When regaining HP after falling to 0 Hit Points, you are Slowed until the end of your next turn.

Notes: Bonus: Temporary Hit Points, Poisoned, Healing, Debuff, Utility