Proscription:

During the dictatorial reign of Sulla, the word took on a more sinister meaning. In 82 or 81 BC, Sulla instituted the process of proscription in order to purge the state of those supporters of his populist rivals, Gaius Marius and his son. He instituted a notice for the sale of confiscated property belonging to those declared public enemies of the state (some modern historians estimate about 520 people were proscribed as opposed to the ancient estimate of 4,700 people) and therefore condemned to death those proscribed, called proscripti in Latin.

Basically Sulla said if you kill these people on these proscription lists then Sulla will split their property with you.