Being a digital TCG, Hearthstone can implement random effects that a physical game would have a difficult time duplicating. Nothing demonstrates this better than Yogg-Saron, Hope's End.
I don't actually own a Yogg-Saron (at least, not yet) as he hasn't shown up in any of my packs, and I don't want to spend the dust crafting him when there's still other legendaries on my wish list. And yet, several of the most memorable games that I've played since the Whispers of the Old Gods release have featured old Hope's End.
Recently, I was playing my Warlock deck with Reno Jackson and C'Thun. I've mentioned before that I tend to play Arena more than constructed games, but every once in a while I get some interesting card in an Arena or Brawl award pack that just begs to be played. That happened here, when I pulled Lord Jaraxxus from a Brawl reward. So I built this deck, which has a whole lot of stall effects, killing the opponent's minions and staying alive until I can end the game. That usually happens via C'Thun or Lord Jaraxxus.
I was matched up against a Mage, and we had the most boring first few turns ever. Neither of us had a cheap minion to cast, and my hand was full of useless minion removal, as I assume my opponent's was. Eventually we each summoned a few minions, which were immediately demolished by the other side. Around turn 8, things turned up a notch with each of us playing Emperor Thaurissan (died immediately in both cases) and various other larger minions. They all died, but it was taking a toll on each of our hand sizes.
Then I had a few really good turns, which put me into a good position to win. Brann Bronzebeard plus Twin Emperor Vek'lor (that's three 4/6 taunt guys), the Mage countered by freezing them with Blizzard, then my C'Thun hit the table for a nice round 20 damage. A few turns later, the life-saving Mage secrets ran out, I had played Lord Jaraxxus, and my board was full of a horde of 6/6 infernal demons. And then...Yogg-Saron.
At this point, the game is a complete roll of the dice. The Mage had cast a ton of spells through the game, so Yogg-Saron was going to throw a ton of random effects. There are more spells that do damage to "opponent" than to "any target", so my side was going to take more damage...but I had more health and more minions. We sat through a good dozen random effects that killed minions, froze various targets, hit me several times....and then the dice went my way. A Mortal Strike hit my opponent and finished him off.
I got lucky that time, but I suspect that Mage wins more often than not when getting that deep into the game. If I hadn't already cleared out the various life-saving Mage secrets, I very likely would have ended up on the short end. I've seen several other similar Mage decks recently, as well as a Warrior version. Whoever wins, those kind of games stick in your memory.
After a long, drawn-out battle, when all looks to be lost...call on Yogg-Saron. He may not always be on your side, but the end will definitely be memorable.