The top rank tier, awarded to the top of the server each season; a season title, not a permanent state.
Conqueror is held by a limited number of players per server and resets each season. A listing that says Conqueror states the season; the title's badge stays on the profile as history.
A service that raises an account's rank — either by a booster playing it (piloted) or playing alongside the owner (self-play).