Spirit

Spirits show up in many places, and even though sometimes they are controlled or created by a guild, they often form only thanks to the will of the deceased, be it through vengence or other emotions. Some might be bound to a certain location, while others might roam vast areas of Ravnica. Most of them remember only echoes of their past life, and drift with passing surface thoughts and an uneasy feeling of forgetfulness.

Sources:

https://mtg.gamepedia.com/Spirit

https://scryfall.com/card/gpt/2/belfry-spirit

https://scryfall.com/card/rav/3/benevolent-ancestor