Infusion is fusing Vis, or Aspects, and key items with a main item to get an "upgraded" version of the main item (e.g. in creating Boots of the Traveler, Leather Boots would be the main item in the center). To infuse items, one must first create an Infusion altar. When infusing, you need to set up the items exactly how the recipe shows; otherwise, you will have the probability to fail. The same can happen if you don't put an opposing item to another item. In recipes requiring odd-numbered ingredients, it is impossible to match every item to another.
Depending on the type of item you are infusing, the chances of instability will differ. It is, however, possible to reduce the chance of instability by placing certain objects around the Infusion Altar. Such objects include candles, Crystal clusters or Skulls. The location of such items are important as they can either increase or decrease stability. The paraphernalia must be placed symmetrically around the altar in order to increase stability. If it is placed asymmetrically, the chance of instability will increase instead. Items in a 25x25 area with the altar at the centre will affect the stability. The box extends 5 above the matrix (and remember, the matrix hovers 3 units above the ground already), and 10 below it; this allows you to put a lot of symmetry items below your altar out of sight.
In Thaumcraft, only symmetry in the x and z direction matter; therefore, if you had an object in with the coordinates (relative to the altar) [x,y,z] you will have to place another object at the coordinates [-x,y-z] in order to preserve the symmetry.
"Arcane crafting and alchemy can go only so far. Something better is needed to create truly powerful mystical objects.
Infusion crafting is the process of infusing a single object with magical energy and the properties of other objects. For example, you could infuse a stone with vis and a feather and it would result in very light stone.
As is usual with Thaumaturgy, things are not quite that simple. To even get started with infusion crafting there are several things you need: a Runic Matrix, Arcane Pedestal, and a ready supply of magic in form of Essentia."
Later research will allow you to use the infusion altar for another use, enchanting. Using salis mundus, the appropriate item, and some essentia, you can apply any enchantment to an item. The rules for enchanting still apply; for example, you cannot apply both fire protection and blast protection to a piece of armor using infusion enchanting.