This is sort of a guide request.
Although there isn’t a lot we can do to influence it, I’m curious what bonuses we get when multiple tributes trigger at the same time
2 → 2 gems, 1 key
3 → 10 gems, 2 keys
…who can help me fill in the rest?
Has anyone had the insane luck of having 15 or more trigger at the same time?
0-1 Tribute = 0 Gems or Keys
2 Tributes = 2 Gems/1 Key
3 Tributes = 10 Gems/2 Keys
4 Tributes = 15 Gems/3 Keys
5+ Tributes = 20 Gems/4 Keys
Most I have seen is 5 tributes at once. What you get would depend on the kingdoms that gave tribute.
@Mariox Yes, that’s true for gold, souls and glory. But not for keys and gems (as far as I can tell).
@Zelfore Thanks for the info 
20 Gems and 4 Keys are the max. The number of those doesnt go up from that. Or at least can confirm it on 7 Kingdoms tribute. No idea on 8+ Tributes…