Once all Focus Blocks are full of energy, the block in the center will be destroyed, and a sphere will spawn. The size, health and damage of the sphere depends on the block used - iron makes smallest sphere, emerald makes biggest and strongest sphere.
You must provide energy to focus blocks. When everything is ready, you must place one of the following blocks in the center - Iron block, Steel block, Gold block, Diamond Block or Emerald Block. The particles will show that the creation is in progress.
In order to create Companion Spheres, you must place four Focus Blocks in this pattern, where a center is 5 blocks apart from every focus block.
Use them for smelting multiple items. 3 types are available.