Zephyr is an uncommon, albeit not particularly rare, stimulant which increases the physical speed and reaction time of those who consume it. 

The drug itself is usually stored as a liquid and administered by vaporizing and inhaling the substance. It is a strange color, almost appearing translucent like water, but with an unmistakable silver sheen.

Each Zephyr Cartridge carries 5 doses. You may spend a bonus action on your turn to administer one dose, breathing in a small amount of the vapors through a vaporizer or mask.
Each Cartridge costs roughly 25gp, as it is relatively easy to produce, but is highly illegal due to its harmful nature and addictive properties.

When administered through inhalation or consumption, you take 1d4 Necrotic damage, un-reducible in any way, and become under the effects of the haste spell until the end of your next turn.
However, when you loose the benefits of haste, you enter into a state of lethargy. When in lethargy, you cannot move or take actions until it ends,  at the end of your subsequent turn. 

You may additionally, should you so wish, use the Zephyr again while in haste, expending a dose, taking the damage, and then extending the duration by one further round.

However, whenever you consume a number of Zephyr doses equal to your Constitution modifier, you must make a DC 10 Constitution saving throw. On a failure, you become addicted to Zephyr. While addicted to Zephyr, you must use at least a number of Zrphyr doses per day equal to your Proficiency bonus. If you fail to do so, when you complete a long rest you gain one level of exhaustion instead of removing one. Additionally, you only regain half of the normal long rest benefits including hit points, hit dice, spell slots, and class feature charges. You may remove this addiction by having the spells Greater Restoration, Modify Memory, cast upon you, or some other similarly challenging method (DM discretion).

Notes: Damage: Necrotic