So tribute cards work like this:
You scan your card and are given a small bonus for a random thing (Xp gain, gathering skill etc) Your friend scans the card and the power of the card increases a little bit The more powerful a card the greater the bonus The benefit of a card is broken into milestones, to hit the first milestone all anyone has to do is scan the card, after that you will need to pay gold to increase to the next milestone. Milestones increase the power of a card much further, so the more milestones unlocked the greater the benefit of that card for those who have scanned it.
This makes tribute cards ideal projects for guilds and groups. You can make it a regular task for the group to contribute gold towards unlocking the next milestone and for all of the group who scanned it to get the benefits as a result.
Nice @David K?! I just helped raise your #3 currency to rank 2, but I will contribute to this one too when it maxes!