Since the options are lacking in your question, I will write few methods that Stalin used and hopefully it will help you.
Stalin was a very brutal leader, and he used everything possible that he could in order to strengthen his position. He is actually the leader that has killed the most people during his reign, even making Hitler few levels bellow his brutality. Some of the methods he used were:
- Elimination of his political opponents;
- Elimination of people that were speaking against him or the government;
- Imprisonment in the harshest prisons in Siberia;
- Torture;
- Genocide over multiple ethnic groups;