Potion, common (four vials)
Three of the four vials answer their labels. Drinking one is an action: it ends the poisoned condition on you, and for the next hour you have advantage on saving throws against poison. The vial is spent, and they are not replaced.
The third vial is offered as it stands, sealed and whole, and is not warranted to be what its label says. The Sworn Weighers have weighed it against the other three and report it heavier by half a drachm, and decline to say anything further.
Source: Provenance — The Quist Sale