Board Thread:Card Unit Builds/@comment-110.55.4.76-20150219035000/@comment-66.62.115.199-20150219035732

You need to buy ATK arcana/DEF arcana from the in-game store. The arcana costs rare medals, which are obtained by trading rare and higher cards for them.

Each arcana adds 50 of a stat, so in order to calculate how many arcana you will need, take the current number of the stat you are looking to max and subtract it from that card's max stats (HSR and below have a max of 19999, GSR have a max of 24999, H/UR have a max of 29999, and GUR have a max of 34999 [I am not sure about GUR's max. Please correct me if I am mistaken]). Then divide that number by 50 to get the number of arcana you will need.