Arena Assistant is the best app which can help you draft better Hearthstone Arena Decks. Drafting deck is the key to good arena performance. This app can help new players win 2+ more games in average. It shows you not only the value of single card, but also show you the synergies. The app analyzes your previous picks and give you suggestion for best pick which has positive synergies and fit your mana curve.
Arena Assistant will also help you track your arena records, just like the websites "HearthArena", "ArenaMastery", and etc. With the stats, you can understand what your best class is and what your weakest.