So I decided to purchase the Ariana deck to see how it would work, since I knew that an extra Puppet Master, 2 Soulreavers and Mirror Image would be helpful for any Dark Magic deck I might make in the future, plus I wasn't sure if I had the patience to get Ariana through the achievement. Here are my observations so far:
Ariana is brutal against any creature based deck, there doesn't seem to be any clear path for those decks to victory provided you can stem the initial assault. If they play a bunch of little creatures, you can sweep them. A single big creature and you can Soul Reaver/Mirror/Puppet Master it, and Decay Spitter is an all-star every time in comes into play. Even learning the deck such that I made significant mistakes it still seemed remarkably powerful and this was the deck without Atropos in it.
The matchup against Stronghold looks like it should go to Necro. There are a lot of good targets for Puppet Master there, and not a lot of good options for the Stronghold Player once you're slinging poison. I won a match in which my opponent was able to get 3 different Tainted Orcs into play. Another Stronghold opponent appeared to be doing some type of creature-less variant but I ran him over with Time Jump before he could Grand Finale which is what OTK Stronghold decks usually do when they work properly.
The matchup against Haven looks like it should go to Necro. The only Haven player I faced seemed just as unlikely to win as when I was playing Inferno
I did not face a Sanctuary opponent. Having seen Sanctuary before, I don't expect it would have been much of a challenge, except perhaps that lock deck I keep hearing about.
The matchup against Inferno looks like it should go to Necro. I faced four Dhamiria opponents, two were doing the Void Arbiter Lock style, the other two were doing Slowpoke. Against the two slowpokes I won one match on the strength of top-decking Time Jump, and lost the other one quite badly. For the two epic Dhamiria opponents I also split the games. The first opponent and I had a crazy game, such that I had him down to 4 life really early but he had an Earth's Grasp in play so I couldn't just Mirror Image him to death. He kept doing various board wipes and I kept playing out creatures until I finally dealt the final 4. He never got a Nature's Might into play, which I think could have swung it for him, provided he had it early enough. The final Dhamiria Void Arbiter deck was also a fascinating battle of wills. I also got my opponent to 4, but he had the Nature's Might and melee creatures in every spot, which means the only way to get additional damage was via Puppet Master. I came pretty close to having a window, but I wasn't able to hit it. Having Insect Swarms and Earthquakes deal 1 damage to his creaures and 3|2 to mine was pretty gamebreaking, as were the Hellfire Maniacs once they took half damage.
And finally. the matchup against Necro looks like it should go to Necro. Hopefully they will follow through with a nerf to key Necro creatures, so that particular matchup doesn't happen quite so often.
So, in summary, Necro easily wins the matchup against every faction except for Inferno. The Inferno matchup is decent, but only if the person playing Inferno has the epics to pull off either Arbiter Lock or Slowpoke. Without those epics however, the matchup switches back to favoring Necro.
Ariana is brutal against any creature based deck, there doesn't seem to be any clear path for those decks to victory provided you can stem the initial assault. If they play a bunch of little creatures, you can sweep them. A single big creature and you can Soul Reaver/Mirror/Puppet Master it, and Decay Spitter is an all-star every time in comes into play. Even learning the deck such that I made significant mistakes it still seemed remarkably powerful and this was the deck without Atropos in it.
The matchup against Stronghold looks like it should go to Necro. There are a lot of good targets for Puppet Master there, and not a lot of good options for the Stronghold Player once you're slinging poison. I won a match in which my opponent was able to get 3 different Tainted Orcs into play. Another Stronghold opponent appeared to be doing some type of creature-less variant but I ran him over with Time Jump before he could Grand Finale which is what OTK Stronghold decks usually do when they work properly.
The matchup against Haven looks like it should go to Necro. The only Haven player I faced seemed just as unlikely to win as when I was playing Inferno
I did not face a Sanctuary opponent. Having seen Sanctuary before, I don't expect it would have been much of a challenge, except perhaps that lock deck I keep hearing about.
The matchup against Inferno looks like it should go to Necro. I faced four Dhamiria opponents, two were doing the Void Arbiter Lock style, the other two were doing Slowpoke. Against the two slowpokes I won one match on the strength of top-decking Time Jump, and lost the other one quite badly. For the two epic Dhamiria opponents I also split the games. The first opponent and I had a crazy game, such that I had him down to 4 life really early but he had an Earth's Grasp in play so I couldn't just Mirror Image him to death. He kept doing various board wipes and I kept playing out creatures until I finally dealt the final 4. He never got a Nature's Might into play, which I think could have swung it for him, provided he had it early enough. The final Dhamiria Void Arbiter deck was also a fascinating battle of wills. I also got my opponent to 4, but he had the Nature's Might and melee creatures in every spot, which means the only way to get additional damage was via Puppet Master. I came pretty close to having a window, but I wasn't able to hit it. Having Insect Swarms and Earthquakes deal 1 damage to his creaures and 3|2 to mine was pretty gamebreaking, as were the Hellfire Maniacs once they took half damage.
And finally. the matchup against Necro looks like it should go to Necro. Hopefully they will follow through with a nerf to key Necro creatures, so that particular matchup doesn't happen quite so often.
So, in summary, Necro easily wins the matchup against every faction except for Inferno. The Inferno matchup is decent, but only if the person playing Inferno has the epics to pull off either Arbiter Lock or Slowpoke. Without those epics however, the matchup switches back to favoring Necro.