Shards
They have the ability to pull people out of dungeons at the cost of Magic Crystals, and the ability to contact people with messages like in Opening.
Shards have a default upkeep cost of 1 point per week connected to the network. Transferring out of a dungeon uses a week worth of points.
Shard Mods
Various upgrades are available for shards. These upgrades cost gold pieces upfront and increase your shards upkeep cost.