Combining multiple cards with the same name will increase the cards' level, which, in most cases will change the stats of monster cards. Combining summoner cards and leveling them up, will allow you to play higher-level monster cards.
Step 1: The first step is to go to your card collection by clicking on the Cards icon as displayed circled in the screenshot to select the card in that you wish to level up.
Step 2: If you click on the "Stats" tab, you will see how many cards are required to level up this card. You cabn also see the changes in stats and abilities in this tab. For example, 30 Antoid Platoon cards are required for the combination of a level 4 version of this card. The card will go from 1 to 2 attack power and go from 2 armor to 1 armor, compared to the level 3 version. This is because attack and ability attributes are often considered greater properties than other attributes. So to combine the level 3 card into a level 4 card we will need to add 16 more cards to go from 14 card to 30 cards.
Step 3: Now that you know what stats will change and you decided you want to combine the card into a higher level card, you go to the "Cards" tab.
The BCX column is displaying the number of single cards that are currently on the cards you are planning to combine. Since 30 cards in total are the amount we needed for level 4, we need to add 16 other cards to the level 3 card in order to achieve level 4. This could be 16 single cards or any combination of 16 BCX. In this example, we will combine a 14 BCX card with 16 pieces of a 1 BCX card. You could also combine a 14 BCX card with another 14 BCX card and a 2BCX card, or any other combination as long as you add up cards to 30 pieces.
Step 4: Select cards up to the amount needed for the next level.
Step 5: Press the "Combine" icon
Note: Technically, pressing this button will send a command to the Hive Blockchain to combine all the unique cards into 1 unique card.
Step 6: In the window that is asking if you are certain that you would like to proceed with this action click on the "OK" button.
Note: you can also do a final check here if you counted well. If you combined just enough cards to reach that level and did not add an extra card, the number in front should always say 0.
Step 7 (Optional): You may get a pop-up to verify this blockchain transaction depending on the way you verify your Hive Transactions
Once the transaction is fully submitted and the page reloads itself, you should now see your cards' level and stats have changed.
This card should now be playable within appropriate formats, league level limts and rulesets that would allow for its play and will be played at this new level as long as a summoner of a high enough level is able to summon it. Else the card may only play to the highest level version that any summoner or league level limits will allow for.