4 bonus tokens you can mix with the bonus tokens of the base game. Each of them gives you more rewards (a combination of the usual rewards as a built action, an influence action, extra resources, etc) compared to the ones from the base game, but at the cost of reducing the effective power of your action.
These tokens were free if you pre-ordered Founders of Teotihuacan from the Board&Dice webshop during a certain period and they can now be bought from their webshop. This promos was later available as part of the Game Boy Geek Season 10 Kickstarter.
For more information, please refer to the BGG listing.
Part of the Game Boy Geek Promo collection.