Aura Nodes are part of Thaumcraft. There is one in every chunk. They stabilize the Vis in the Aura. The Vis in the Aura is what charges Wands, Infernal Furnaces, and produces Infused Stone. When Vis from the Aura is used, the Aura Node's Vis level drops, causing near Aura Nodes to send more Vis to it, to balance them out. When Flux gets into a local Aura Node, the Vis gets slowly replaced by Flux.