The special items category of your inventory contains all the items that don’t fit one of the other categories. Things like transfers, renaming cards, building consumables etc. Some of these items are available via quests, some are diamond shop only.
Battle Codex. This is used to upgrade the Bannerman Hall. You will get 10 for free to start, after that each one costs 15 diamonds. Each level of the hall requires an increasing number of Battle Codex.
Money Lender’s Contract. This item is used to upgrade the Iron Bank. Each level of the bank requires an increasing number of contracts, each one is 20 diamonds.
Book of Confession (previously Shackles). A consumable required to upgrade the dungeon. Each level of the dungeon requires an increasing number of books, each one costs 15 diamonds.
Mask of the Faceless Man is a consumable required to upgrade the Hall of Faces, as with others each level requires an increasing number of masks. Diamond cost is 15 per mask.
Expedition and Weirwood
Spirit of Weirwood tree. This item adds 120 stamina to your character. It is available from some of the chests in the Elite Weirwood Trials and the diamond shop for 2,000 diamonds. Note your stamina bar can exceed its max amount. So if you have 10 stamina and use a Spirit consumable you will have 130/120 stamina (this is before researching the stamina limit increase)
Motivation (they seem to be changing this to Mobility). This item will add the amount shown on the icon to your Motivation for attacking Rebel Leaders (the horses on the world map). These are available from quests, chests and the diamond shop. NOTE These items will NOT exceed your maximum motivation like the Weirwood item does. If you use one which would cause you to go over the overage is lost!
Random transfers will, as the name suggests, randomly move your castle to another location on the map. Some higher level players use these to find hives or a group of other player castles to attack for experience. Be careful using these as a new player, while they can help you escape danger they can also drop you right next to a large alliance where you’ll become a farming target! These are used directly from your inventory. These are available from quests and the diamond shop for 500 diamonds and from the Alliance shop for 60,000 alliance coins
Precise transfers allow you choose a specific spot in your kingdom to move to. They are available from some quests and the diamond shop for 1,500 and from the Alliance shop for 270,000 alliance coins To use one find the location you want to move to, click an empty spot on the map. In the dialog that pops up choose “Relocate”