Board Thread:Question and Answer/@comment-25874611-20141215172613/@comment-183.90.37.7-20141215185816

you use normal cards and arcana(s), then spam upgrade all the way until 19999. note that the higher the card level, the more gold it costs per upgrade.

sometimes you get arcanas in events that adds 500 to a certain stat, they're basically equal to 10 arcanas or 1800 medals and can't be attained anywhere else (i think)

dark santa's skill reflects on the total attack of your card, so yes modified damage will be affected by the skill. but you might want to max dark santa's skill level before her atk because the +271% boost will change to a +437% boost, and would add a lot more damage if you used the same amount of medals to buy arcanas instead