I started playing this wonderful game about two weeks ago and finally - on the 9th try - beat Anduin !!
I am playing single handed solo with just the CORE set and the single sphere, 30 card decks that come with it. I thought this may be the best way to get familiar with the strengths and weaknesses of each sphere before I tried my hand at deck building. After failing 2-3 times with mono Tactics, Lore, and Leadership decks, the Spirit deck is the one that helped me conquer this quest (on the first try).
Now on to some duel-sphere decks -- this is exciting! It feels like I've graduated to the next level....