I hope that would be something you wanted to know all the time.
Please take a look at above image. You will see Capture Rate. It is important but it is not related to the DEC reward bonus. I think it is a base of your DEC rewards and you will also need to take card of it. The higher DEC capture rate the more DEC rewards you will get.
In DEC reward bonus section, you can see 4 items. They are Win Streak, Gold Cards, Alpha/Promo cards and Guild. So all these items are important but you may overlook.
Win Streak: This is simple. As its name implies whenever you win three or more times consectitively you will get Win Streak Bonus. You will get 10% for third consecutive win and another 5% for next consecutive wins. But It will be difficult to win many battles consecuitively. It you lose or draw you need to start over and Win Streak count will be resetted. So this is really difficult and depend on your luck, your opponents and your deck.
Gold Foil: This is also simple. System will count how many gold cards you used in a battle. If you use 3 gold foil cards in the battle you will get 30% bonus. If you use one gold foil card you will get 10% bonus. System will give you 10% bonus DEC for every gold foil card you used. Maximum is 70% I think because you can only choose one summoner and six monsters for a battle.
Alpha/Promo cards: This is really what I want to write in this post.
I think you will know about Alpha cards and Promo cards. Alpha cards are very ancient and rare. I don't have this cards too. So I will write about Promo cards.
Do you know which cards are Promo cards.
Do you notice that you will earn more Dec by using this cards in the battle.
If you have cards showing in the above image, try to use these cards and you will get 10% bonus for every cards you use in the battle. But one thing to remember if you lose you will not get the DEC rewards at all. I only show the normal foil there will be gold foil version as well.
Guild: This is also important and you should have a good guild. Max limit for Guild bonus is 20% and I got 9% out of 20% so this is good for me. Thanks to 
There are other facts influcing you DEC rewrds. This is League. The higher the league you play the more Dec rewards you will get. With the new changes it is more important so I also trying to reach diamond league to get more rewards. But My CP is short for more than 20k so I still need to fill it.
If you want to play Splinterlands. Please use following link: