I had a game this morning that perfectly summed up my frustrations with Hearthstone. I was playing tempo/totem shaman and my opponent was some kind of spellpower druid.
He got a good Innervate/Wild Growth start, but I got awkward draws and was a bit slow in the early game. I managed to hold on and get board state established in the mid game, but he was stopping me from really getting anywhere with good use of removal spells. I didn't over-extend, thought hard about trades vs face, kept back my own removal for the big threats, and generally kept the game on a knife edge despite it going well past my deck's ideal game length.
And then he played Yogg-Saron and a bunch of RNG shit happened that ultimately ended up favouring my opponent by sheer, dumb luck and he wins two turns later.