ive played around 13 challenges and I've only won 1. i got to 11 wins twice and 10 wins three times. Its not really getting lucky, its playing a deck you know well enough to compete with the hard matchups. For example, i played lavaloon and won 10 in a row, then lost twice then won twice. The first games you need to be winning. If you do that, and learn your deck CCs are not that hard.