Wand Focus (Thaumcraft 4)

Wand Foci are a major part of Thaumcraft 4 that allows the player to "cast a spell." Their uses range from basic offensive capabilities to building utilities. Using a wand focus will consume vis (either per cast or per tick if the spell is sustained).

Focal Manipulator
With enough research the player will be able to craft a Focal Manipulator which will allow them to upgrade their foci to consume less vis (Frugal), increase their power (Potency), and other upgrades.