In order to complete Advanced Foci, or to even be able to craft them, you need to get into Arcane Infusion.
Clicking on “Basic Infusion” will unlock this research for you. There is no need to do any research just yet.
Going back to the main page of Arcane Infusion will give you two more stages you can get into. Currently, you only need to unlock Infusion:
You need to scan a few things, do a little research and have the following in your inventory:
Feather Stone Block Phial of Essentia - Aer
Phials can be filled with any type of Essentia by right-clicking any Jars full of Essentia with the Phial. Once you have these, complete this research. The next stage requires you to craft a Runic Matrix. The materials are simple, just requiring some Arcane Stone Bricks and Nitor (any colour), and you should be able to create this without any issues.
Once you have your Matrix complete, you need to craft the Mystical Construct. This is a multi-block structure. You need::
Once you have these put them as follows:
Once built, right click the matrix with Salis Mundus:
Now you may be thinking that you can start crafting with this straight away, but there are a few things you will need to know about before attempting anything. There are a few other requirements and some fun little mechanics involved.
Since each infusion requires components outside of the Altar, you need to put 8 (it can be 6, which is symmetrically better for some recipes) Arcane Pedestals around the Altar, two blocks away from it:
Placing the items that you need for Infusion crafting in a symmetric location will reduce instability.
Place “occult” things such as candles and mob skulls around the altar (symmetrically) to reduce instability. More than a total of 12 “occult” items will cause instability
Jars of Essentia (easily crafted in the Arcane Workbench with Glass Panes and Slabs)
Each craft will also need Essentia. This is why you will need Essentia near the Altar (the amount of jars depends on what you are infusing). They can’t be too far or close to the Altar (12 blocks away from the altar is the max distance). Having your Jars all around the altar would be easiest, so you can see what you have and what you need.
To craft the Advanced Focus, you need to place a Blank Lesser Focus in the middle of the Altar and then place the following around the altar on the other pedestals:
When looking up the recipe for crafting this focus you will notice at the bottom of the page it will warn you that this has Minor instability. You do not have to go to crazy about balancing your altar for this craft, as long as it is symmetrical (see above picture) then it should be fine, the alter may become a little unstable but the process is fairly quick and should not stop.
As you craft different items in the alter this instability can be higher (Crafting the Vis Amulet has high instability) and lower, just be sure to check this before crafting and take precautions.
Right-click the Matrix with your Caster’s Gauntlet to start the infusion process:
Once it has finished, collect your Blank Advanced Focus from the middle of the Altar. You need to do some research at the research table.
You should be able to complete the section: Advanced Foci.