So, while I know similar ideas have been proposed, none of them addresses the main concern of the developer, that of heroes and items being sold on the black market through Facebook, Line, etc.
What I propose is giving the stronghold the function of alliance trading post; and the establishment of the alliance loyalty point system.
Participation in alliance wars and Titan battles would generate loyalty points. Loyalty points can be spent in the alliance trading post for items and hero trades. Allow both crafting material and ascension material trades.
Loyalty points in war and Titan battles would be awarded 1 points per flag used, plus a bonus based on points earned in war, and rank on Titan (D = 0, C = 1, B = 2, A = 3, A+ = 4) for both defeated and escaped Titans to encourage maximum effort even on escaping Titans.
All loyalty points are lost if you leave an alliance. And you cannot use loyalty points acrued until you’ve been in an alliance for 30 days.
Reclassify Hidden Blade, Sturdy Shield, Orb of Magic, Warm Cloak, Trap Tools, Compass, and Fine Gloves as 4* materials.
Reclassify Damascus Blade, Tome of Tactics, Farsight Telescope, Mystic Rings, Mysterious Tonic, Poison Darts, and Royal Tabard as 5* items.
Items, materials and heroes must be traded, and can only be traded for items/mat of the same class and star rank. Thus, if you don’t have a 5* ascension item, you can’t trade for one. Leveled heroes cannot be traded. Create an option to reduce a hero to 1/1, unless the hero is maxed, with no items/mats recouped.
It costs loyalty points per star rank for items/materials, so 1* = 5, 2* = 10, 3* = 15, 4* = 25, 5* = 50.
Hero trades. 1* = 25, 2* = 50, 3* = 75, 4* = 100, 5* = 150
You cannot initiate a trade with a specific player. Trades are posted item offered, item wanted in the trading post, and any alliance member can make the trade. Both parties must have the loyalty points required.