Cyphers

Cyphers are numenera objects that can trigger a powerful effect, but can only be used once. Cyphers and your Cypher Limit score are displayed in a special section of the Inventory screen. Take care not to accumulate more cyphers than your Cypher Limit or you will experience unpleasant side effects.

That effect is a Cypher Sickness fettle. The strange forces emanating from Cyphers cause unpredictable, but always harmful, effects when they interact. To reduce or eliminate Cypher Sickness, use some of your Cyphers, sell them to a merchant, or give them to another party member.

Tabletop mechanics
Cyphers are in many ways the most important aspect of the Numenera. So much so, that the working title of the game system itself is the Cypher System. Cyphers are one-use, cobbled together bits of technology that characters frequently discover and use. When the PCs come upon an old device, defeat some artificially enhanced or designed creature, or simply sift through the ruins of the past, they can scavenge a handful of new cyphers.

Because the technology of the past is unknowable, cyphers are often determined randomly. A GM, however, can place them intentionally as well. They’re one-use cool powers that can heal, make attacks, or produce effects like nullify gravity or make something invisible. The sky’s the limit. But they’re always consumed when used and they cannot be hoarded. Collecting cyphers together in one place, or carrying many on your person can potentially have a detrimental effect–from the long term (illness) to the short (explosion). So essentially, characters only carry a few at a time. However, they are found with such regularity that players can be pretty free with their use. There will always be more. And they’ll have different benefits.