The Ambassador is also head of the Foreign Affairs, charged with the task of handling all matters relating to the home city (and often homeland guilds) that also involve a neighbour; be it city or guild. Ambassador can be considered a synonym for Foreign Minister since the rank and responsibilities cover all foreign affairs. The Ambassador and his or her aides - often an aide will be charged with the relations with a specific city or group as area of authority, though ultimately the Crown-bestowed mandate lies with the Ambassador alone.
The Ambassador powers include declaring WAR or accepting PEACE, negotiating and signing treaties, marking a particular city or guild as ENEMY or FRIEND, overseeing foreign affairs, sphere of influence, tributes and all military affairs alongside the Field Marshall and Prince/Prime Minister/Minister of State.
The Ambassador plays a role in mediating citizenship changes, particularly for the very young when a junior wishes to join the city or believes his/her future lies in another city: in smoothing the transitions and ensuring repercussions are kept reasonable. It is frowned upon by the Gods to act harshly or punitively to a youngster trying to find the right city for a future Avalon life - given the arbitrary nature of their birth - and the Ambassador's role includes helping the junior where citizenship/guild-membership is concerned.
Citizens of senior standing of course are another matter: loyalty and constancy versus fairweather commitment and defection become situations to be treated on individual merit and though the Ambassador may play a part in these affairs, it is not a formalised area of authority (unless designated so by a city's current government).
Ambassadors should be familiar with HELP TREATIES, HELP RATIFY, HELP DIPLOMATS and HELP DUTIES (as should all ministers) covering those duties and jobs falling under the Ambassador and Foreign Minister's remit.
Those with Ambassador rank or citizens with aideship to the Foreign Affairs ministry can peruse CITY HELP AMBASSADOR and CITY HELP FOREIGN for specific commands while HELP CONQUEST and HELP SUPPLICATION document the sphere of influence and war/peace powers; HELP FEELINGS the relations with other cities and HELP DIPLOMAT covers the various levels of diplomatic privelege extended to foreigners and under the command of the Crown and the Ambassador alone.