[KissBlade]

Empower your mages and make boosters by either trading for them or getting them yourselves. As you feel your gold is getting less than important, use three scouts to blood hunt your 5-9K range population provinces for some blood slaves to empower into blood. Site search thoroughly EVERYTHING either with indie mages or mercenaries.

try to concentrate ESPECIALLY on grabbing the sorcery branches (astral, death, nature, blood) they tend to get incredibly strong late game.

Lastly diplomacy is definitely valid, make sure you're looking at the two most important graphs though when determining top nation (research and Gems)