The Glow has the ability to create glowing lights that look much like hundreds of fireflies. It is one of the most mild cards, not creating distress or panic to anyone before it's capture, but forming into a pretty view instead. It's main body is the same depicted in the card: a small green fairy holding a dandilion flower. The Glow is under The Light
The Glow was captured in Episode 18. Sakura first encountered it in a prophetic dream where a small fleck of light rests on her finger. She forget's the dream initially, but then remembers it when The Glow cast a small speck of light to fall on Sakura's finger during the festival at the Tsukimine Shrine. The Glow then was captured by Sakura with no resistance.
The Glow is transformed into a Sakura Card during Episode 67. Eriol had conjured a horse that cut the electricity to all the lamps to the Tsukimine Shrine during a festival. After Sakura and Syaoran subdued the horse with the combined effort of Syaoran's magic and The Thunder, Sakura uses The Glow to reilluminate the Shrine while the festival is still underway.