1. Bag of Sharing
A wondrous item, probably of uncommon rarity, that consists of a pair of bags that are magically linked to the same extradimensional space. When one bag is open, the other remains closed. Anyone can reach in the bag to deposit something into it, and then the owner of either bag may open their bag (when the other is closed) to access the object. Storage would be small. When either bag is on a different Plane, neither bag can access the extradimensional space, and both appear as mundane leather bags.
2. Background for the Bag of Sharing
Something to do with powerful spellcasters or creatures either modifying regular bags of holding, or creating these bags in trios and disseminating them to places where adventurers and the curious can find them. The idea being that the mysterious creature holds one of the linked bags, and can steal items from the other bags or deposit items into them for the adventurer to discover, like a Ring of Recall (see below). More mundane uses would be for spies or agents of some group or another who need to sneak in magical objects, or that need to steal small things and make them disappear right away so as not to get caught (an ally with the other bag would open it to take the stolen object out, presumably).
3. Ring of Recall
A pair of rings that can be worn or attached to objects of medium size or smaller. One ring is the Primary ring, the other (or all the others) is a secondary ring. Whenever the owner of the Primary ring wills it, she can recall the wearer of the secondary ring/any object attached to the second ring or that the ring is placed inside of (like a treasure chest). This occurs via teleportation.
4. Background lore for the Ring of Recall
Used by powerful kings and queens to summon guards at a moment’s notice. Used by thieves or the heads of evil cabals of merchants to steal cargo, or to force anyone shipping their cargo to pay for what they “lost”. Shared between loved ones or given to children to wear on necklaces. Used by nefarious bad guys and hungry dragons to summon unwary adventurers who put the rings on. Thieves drop the rings into the coin-filled pouches worn by their marks, then teleport the pouch to themselves when the time is right.
5. Could the Wand Mage archetype have the ability to trade spell slots for Superiority Dice?
6. Figure the Wand Mage starts with two superiority dice, and these are d4s.
7. They can have up to five superiority dice at any one time. To gain more dice, the Wand Mage (Combat Mage?) must cast spells into her bonded wand.
8. 2nd for a d4 superiority die, 3rd for a d6, 4th for a d8, 5th for a d10, 6th for a d12.
9. I figure 1st levels spells could grant a d2, and 7th through 9th only grant a d12.
10. The bonded wand would store the spell energy, and anytime the Combat Mage performs a combat maneuver (either as a spell or as a physical maneuver, see the post above this one) she expends energy from the wand in the form of a superiority dice.