To be able to play Tower Duel with a teammate, you must first belong to one. For this you can create or join an existing team. We invite you to visit our articles "How can I create a team?" and "How can I join a team?" for more information about the steps you'll need to take.
If you are already part of one, in the "My Team" tab, you will be able to see the list of members and their activity status, that is, if they are "Online" or "Offline". Next to their names will appear the medals they have, their levels, and a third option marked with the icon of the Tower Duel.
By pressing on the latter, you will be able to play a game of Tower Duel with the selected partner, as long as they are "Online". For more information on this game mode, we recommend you visit the article: "How do I play Tower Duel?"