You conjure the black spirit in an unoccupied space that you can see within range. The spirit is classed as a Fiend. The spirit is invisible to all creatures except you and can't be harmed.
The spirit's only method of movement is a flying speed of 15 feet. The spirit can enter and occupy the space of another creature. The target can pass through small holes, narrow openings, and even mere cracks, though it treats liquids as though they were solid surfaces. The spirit can't fall and remains hovering in the air even when stunned or otherwise incapacitated. While the spirit is within 100 feet of you, you can communicate with it telepathically.
As an action, you can temporarily dismiss the spirit. It disappears into a pocket dimension where it awaits your summons. Alternatively, you can dismiss it forever. As an action while it is temporarily dismissed, you can cause it to reappear in any unoccupied space within 30 feet of you.
* - (a thread and a wisp of smoke that must be consumed by fire)