Mods/Thaumcraft/Infusion

Arcane Infusion is the "advanced course" in Thaumcraft's magic, by which players can build the most powerful items available.

Starting Out
In order to proceed with infusion, you should have researched and built the following items and structures:
 * At least one gold-capped greatwood wand.
 * An Arcane Furnace (not to be confused with the Infernal Furnace). This will let you distill the various essentias used for infusion crafting.
 * A collection of jars and void jars, which you can stock with essentia over time.
 * Optionally, an Arcane Centrifuge.
 * At least 6 Arcane Pedestals (you can make more later). Note that one of these will go in the center of the Altar.  (See "Symmetry", below.)
 * A number of "stabilizer objects", try to start with at least 10 or a dozen. You have three options here:
 * Crystal clusters tie up your precious aspect shards, but you probably can make them already. Their elements don't matter, so feel free to use whichever shards you have a surplus of.
 * If you have additional mods providing mob heads, you can use those.
 * Magic Candles are most generic and cheap: You will need to research the Magic Tallow recipe, but then candles can be made with the Cauldron and the Arcane Crafting table.  They require only Rotten Flesh, Praecantio essentia, and string.  You surely have an excess of rotten flesh from fighting zombies, and can get string in the usual fashions.  You can get the essentia needed by distilling greatwood logs. If you somehow have no greatwood, you can scavenge some Praecantio by distilling magical junk from zombie and skeleton drops (enchanted armor, weapons and/or bows), and/or from fishing (enchanted bows and fishing rods).  If you have beaten a Nether Fortress, distilling netherwart gives a plentiful supply of Praecantio.  Over time, you should make more candles, for advanced infusions 100, 150, or more of them can be useful.
 * An altar area surrounding the altar This should be generally safe from mobs and other interference, but the central area (altar and pedestals) needs to be open to the sky.  You will certainly need at least a 9&times;9 space, but it's worthwhile to make the space larger: 13&times;13 is reasonable, and the useful area can extend up to 19x19.
 * It is good to have space beneath the altar for a "candle room" centered horizontally on the altar. Plan for a space at least 11 or 13 blocks on a side, and up to 6 or 8 blocks deep.  You don't need to dig that out up front, just make sure you have room to do so later without falling into a dungeon or somesuch.
 * And finally, the Infusion Altar structure itself, capped with its Runic Matrix and activated with your wand.

Setting Up
Having set up your Altar with space around it, you need to place pedestals for objects. One pedestal will go in the center; this is where the item goes that you are infusing stuff "into". The jars of essentia you're using will go nearby; their exact placement isn't important, but they need to be within 9 blocks of the Runic Matrix. It's entirely reasonable to stick your essentia storage, and even your Arcane Furnace, near the Altar (but leave room for the pedestals). Eventually, you'll have "essentia mirrors" which let you put your storage anywhere.

Pedestals
The pedestals around them are where the additional ingredients go: These need to be arranged with 180-degree symmetry, that is for each pedestal, you need to match it with another pedestal on the same Y level, but the same distance on the opposite side in both X and Z.  Each unmatched pedestal drastically increases instability (see below, but it's bad), by one or two categories. Given the pedestals, each pedestal occupied by an item should be matched by an occupied pedestal. However, some recipes have an odd number of items. You can't avoid the extra instability from the one unbalanced item, but you should have a matched pair of pedestals, with the odd item mostly-matched by an empty pedestal.

This gives a lot of flexibility, but there's another issue: You want to be able to watch all the pedestals, and quickly get to them to replace items as needed in case of a problem. So, while the infusion will work okay if you put eight pedestals in a box around the altar, it will be harder to keep an eye on and get to all the pedestals. It's better to keep them in two groups on opposite sides, so that you can watch from a third side and never have to run around the altar. Similarly, the pedestals don't actually have to be on the same Y level as the altar, but it will be easier to work with them if they're all on the "obvious" level.

While it's okay to just leave eight pedestals out, that can be confusing if you're using fewer items, and there's some risk of accidentally putting or replacing items in the wrong (unmatched) positions, That's not as bad as an unmatched pedestal, but it does hurt. So it's worthwhile to mine away any pedestals you won't be using, and replace them as needed for each infusion.

For the following diagrams, the gold blocks are the altar itself, stone blocks are "good" pedestal positions, red blocks are "bad" pedestal positions.

Instability
Instability starts at a value depending on the recipe and symmetry, then increases over the course of an infusion. The higher the current instability, the greater chance (each tick) of something bad happening: Flux lightning, knocking an item off the pedestal, producing flux, melting an item into flux, or tainting the player.

Each recipe has a "starting" instability, which has an internal numeric value but is shown as a category: "Negligible" corresponds to an instability value of 0 or 1, "Minor" to 2 or 3, "Moderate" to 4 or 5, "High" to 6 or 7, "Very High" to 8 or 9, "Dangerous" to 10 or more. An unmatched item adds 1 to the instability (and some recipes require an unmatched item), an unmatched pedestal adds 2, and these do combine. It takes 10 properly-matched stabilizer items to counter 1 point of instability.

Instability grows randomly over the course of an infusion. The chance of increase depends only on the recipe instability, so stabilizers will not slow or prevent this increase, only reduce the total. However, the chance to increase is checked each time a point of essentia, level, or item is consumed, thus recipes which cost a lot have more opportunity to increase. Note that doing Infusion Enchantment or Runic Enhancement on an item which is already enchanted or enhanced increases the cost, and thus the overall increase. Also, any problems which delay the infusion (items that go missing, running out of essentia, or discovering that an item is "imperfect") will make things worse the longer they remain unfixed. Instability never goes down -- if things are getting really out of hand, abort the infusion (by removing the central item) and start over.