Trade Tokens allow you to swap cards with your Clanmates... even Legendary Cards!
You'll find Trade Tokens in War Bounties (the new Clan War reward), Special Challenges and the Shop.
A Trade Token is required to initiate a trade, but not to accept one.
If you start a trade and then cancel it, or the trade is cancelled for any reason, you get your Trade Token back! Trade Tokens are only consumed when the trade is successful.
See you in the Arena,
The Clash Royale Team