1) Enrich maps to make exploring more fun and engaging.
Right now, I explore in order to grab a few free resources here and there, to find out where world portals are, where my enemies are, and to build cities. I think it'd be great to include more world "fun points of interest", such as a tavern to visit to buy items/recruit heroes, encounter wandering mages who can teach you a spell for a price, lairs you can enter and explore where a powerful boss creature lives protecting some nice loot, fountains that bless Great Mages or Lords with random effects, individual forts that produce unique units (which then would need to be defended!). I think this would also compliment the Lords concept, as the Lords would generally be the "player avatars" then doing the exploring and reaping the benefits.
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3. More Artifacts, or, Artifacts with Enchantments!
Now with Lords and artifacts, while loving them, I'm also beginning to quickly grow weary of the repetitiveness. The world event where artifact chests appear is cool... though when half of all the loot are Combat Brooms or Swords of Truth, it becomes disappointing. There are so many spells and affects available, I think it's a low hanging fruit to greatly increase the artifacts available, if only by simply adding a chance for an artifact to be generated with a random spell affectation. It'd be great to find a Sword of Truth... that also was randomly generated to grant the wielder a Frost Weapon Enchantment! There could be even more rare randomly generated charts where an item could even grant the Lord multiple enchantments.