The Crystal Core is used with Obsidian Totem blocks to move Aura nodes. Its construction is unlocked by researching Basic Aura Manipulation. It is used to move the closest node within 24 blocks, and can be a very useful tool. It is worth noting that breaking a Crystal Core that has been placed will not return a whole core, only the Nether Star and Shards used in its construction; not even an implement with the Silk Touch enchantment will prevent this. Additionally, some of the shards will change from their original types to Dull Shards.
Bug: When used on a Crystal Core, the pick block feature in creative mode gives an air shard cluster instead.
"You have discovered the secret to moving aura nodes. Unfortunately it has proven to be quite difficult and expensive.
You first need to create a Crystal Core. This fragile, but magically charged structure is capable of bending the aura around it. For now you will simply use it to draw nodes towards it.
Crystal cores are very fragile and you must make sure to place them in the correct spot the first time. When broken they shatter into their component parts and need to be rebuilt.This could lead to an increase in flux in the area."
This requires you to research Basic Aura Manipulation.
When placed in a certain arrangement shown in the Thaumonomicon, you can move the closest node within 24 blocks. The Wand of the Thaumaturge (and also Wand of the Tinkerer if you have Thaumic Tinkerer installed) is/are the only wand(s) able to cast this strength of magic, as it is the only one that holds over 300 vis. This is an expensive, but useful, tool.