Other names include: Black Sage, Croneswort, Wormwood or Herb of St. John.
When dried and burned as a smudge it is often used to help open up access to the higher realms, to stimulate dreams, vision and clairvoyant abilities.
The smoke is a kind of herbal and sweet and a little bit less dense when compared to the smoke of Californian white sage. Then energy feels lighter and maybe a little more "floaty" than sage. Maybe that is part of the reason it is used by some to aid astral travel.
In the Native American tradition mugwort is especially used to keep out negative and evil energies.