Quest issuer
An interesting dimension to explore for a strategic turn-based strategy game would to give the player the ability to be a quest issuer, i.e. flipping a normal game family (RPGs) where players do quests.
These quests could be:
Diplomacy
Spying
Exploration
Covert ops
Rescue person
Steal object
Steal information
etc
The player would have an incentive to offer good rewards for quests to attract the best adventurers. Similarly, the player could look to nurture a group of adventurers (who would gain experience), i.e. not sending them on foolhardy quests, in order to retain their skills for useful quests.
Groups of adventurers would evolve over time (i.e. gaining and losing members), and could defect from one player to another.