The civilization with the most Envoys on a city-state, and at least 3 Envoys, is considered that city-state's Suzerain. There can be at most one Suzerain; ties are not allowed. If nobody has Envoys on a city-state, there is no Suzerain. The Suzerain gets several significant benefits:
Unique Bonus: This is a powerful bonus awarded to the Suzerain which no other city-state will provide.
Suzerain Diplomacy Bonus: You gain a base of +1 Diplomatic Favor every turn. The city-state follows you into war and peace with other players. City-state lands become friendly territory. Your units can move there, heal there, and upgrade there. Your Builder units may improve city-state tiles. See 3 tiles around the city-state. Can pay Gold to temporarily take control of the city-state's military. Gain ownership of all the city-state's resources.
Suzerain
The civilization with the most Envoys on a city-state, and at least 3 Envoys, is considered that city-state's Suzerain. There can be at most one Suzerain; ties are not allowed. If nobody has Envoys on a city-state, there is no Suzerain. The Suzerain gets several significant benefits:
Unique Bonus: This is a powerful bonus awarded to the Suzerain which no other city-state will provide.
Suzerain Diplomacy Bonus: You gain a base of +1 Diplomatic Favor every turn. The city-state follows you into war and peace with other players. City-state lands become friendly territory. Your units can move there, heal there, and upgrade there. Your Builder units may improve city-state tiles. See 3 tiles around the city-state. Can pay Gold to temporarily take control of the city-state's military. Gain ownership of all the city-state's resources.