AuraControl is a Thaumcraft 6 addon that allows blocking (or allowing) the generation of the Aura by individual biomes. It also provides the ability to restrict generation of crystals and Thaumcraft trees in the same way. This mod is designed for modpack makers and advanced players that want a customized Thaumcraft experience.
By default, this mod does nothing on its own. It needs to be configured for it to have any effect. For more information and an example configuration file, see the project's GitHub page here.
This mod also provides an API for other Thaumcraft addons to use. It records the state of the aura after world generation, allowing the aura to be easily reverted or compared. See the previously mentioned GitHub page for more information.