-Adding on to the evolution part, it is recommended that you should at least enhance both of your cards before moving into the last(4th) evolution. However, only do this for the cards you are planning to use in your deck and the card is has 'rare' rarity or above. Rare cards could be easily obtained or replaced with little cost and I'll explain about the currency a little later.
-In the beginning, I recommend you to spend your attribute points by prioritizing the stamina points. This is very helpful for you to obtain quick leveling speed in the beginning levels. I recommend that you get your stamina to around 100 points before you start focusing on the attack or defense stat.
-Also, when you get past level 5 or 6, for every 2 level you will be able to add and extra 'fellow' which acts as a buddy in your list. Whenever you add a fellow and he accepts the request, both of you will obtain an additional 5 extra attribute points! So try to add someone whenever you are able to.
-Moving into the currency part, most of the player usually conduct trading with the Holy Powder (HP) and Cure Water (CW) as currency. These items could be obtained from either quest or event reward. As of the current version of the game, you will obtain a 'personal' version of this item which could not be traded to other players until you have past quest 10.
-One rare card will usually be sold for 2~3 HPs, but if you look hard enough you could also find some people who sells them for 1HP. A wise choice would be looking for sellers who gives discounts when you buy multiple cards.
-Occasionally you will receive a legend booster pack which allows you to obtain a higher rarity card. It is recommended for you to open it only when there is promotions such as 2x super rare chance or currently there is also promotion that give a free HP.
-If you are able to get high rarity card such as High Rare, Super Rare, or even SSR (super super rare), be sure to look for a community forum to acquire suggestions before you trade it away. Sometimes there would be people who would request a trade with you with an relatively low value compare to the player's market value. Be extra cautious whenever someone offers you a max enhanced card, although the stat may look good, the value of of the cards might not be so. Just try to double confirm with the community and ask whether it is a fair deal. I'm sure there would be many people who will answer you quickly.
-Lastly, remember to use a referral code. It doesn't matter if you used mine or andre's code. You only have one chance to use it and getting something free is always worth it. But of course, I will be happy if you used mine
