Go to the location where the green arrow is in the first image.
Look for the obelisk with the hourglass on the bottom, which is the second image.
The red vertical lines with circles represents an approximate 10 minute period. Every 10 minutes, another circle fills red. You can go to different Realms and each realm is on a different timer, so some Realms may have more or less circles filled. After the entire obelisk is filled red, the obelisk top will shine, as shown in the image, and the portal next to it will be active.
Step on the portal, and you will have access to a hidden market run by Sed Talam. On top of the market, there is a card trainer named Tish'mah.