From Twitter Rules: https://support.twitter.com/articles/18311
Harassment: You may not incite or engage in the targeted abuse or harassment of others. Some of the factors that we may consider when evaluating abusive behavior include:
if a primary purpose of the reported account is to harass or send abusive messages to others;
if the reported behavior is one-sided or includes threats;
if the reported account is inciting others to harass another account; and
if the reported account is sending harassing messages to an account from multiple accounts.
Hateful conduct: You may not promote violence against or directly attack or threaten other people on the basis of race, ethnicity, national origin, sexual orientation, gender, gender identity, religious affiliation, age, disability, or disease. We also do not allow accounts whose primary purpose is inciting harm towards others on the basis of these categories.