The Sect begins the game with one player - the Sect Leader. Each night, the Sect Leader can convert one player. This player must be from the village or they won't be converted. Players with other loyalties (e.g. lovers) can be converted to the Sect as long as they fit the above criteria. The Sect Leader can be used, in some circumstances, in a way similar to the seer, being used to find wolves or other anti-village teams.
Players in the sect (other than the Sect Leader) don't have the ability to convert or talk during the night. A very high level of coordination and planning is usually required to win as the sect.
If the Sect Leader dies and a member of the Sect is brought to life by the medium, this player at the end of the game will lose anyway because he was member of the Sect.