by notrub
Further to my vote:Although I listed three spheres, the more accurate answer is two (mostly balanced) plus a third as a trace or partial, to provide select capabilities.
Re: deck construction - I focus on a single deck (solo play, only) to do well on the vast majority of quests (offical and fan made). Doing well is 2-3/4 wins. So far, that has worked with minimal changes since mid KD (so far, heh). Nevertheless, I have not done at all well vs Dol Guldur (1 win in 8 tries, so far). For me, that one may require a highly customized deck coupled to luck. Those with more experience could speak better to the problem, I would guess.