Ambassadors have become invaluable tools of war: let's add some juice to this.
As I understand ambassadors have a boost on the effects of their diplomacy, cool. But who are they ambassador to?
Make ambassadors be tied to an allied or federated realm, on the agreement of both realms. Make alliances and federations break if the realm average sentiment to a realm doesn't meet X. This reduced the risk of alliance blocks, they'll naturally crumble over time without an ambassador to support the alliance via diplomacy in both realms.
It also gives embattled realms the opportunity to grease palms and maybe bribe an ambassador out of office for one who isn't so apt to use their skills against them. Adds intrigue.
