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.
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.