Summary

So, this Big Shaman is 11-3 so far on Ladder at Platinum ... that's a 79% winrate. I think it might be good.

Scrapyard Colossus is just a better hit for Muckmorpher than Big Bad Archmage ever was.

DAY 1 CONCLUSION: 55.2% Winrate over 67 games, despite an 8-game losing streak to end out the day. Climbed from Platinum 10 to Diamond 10.

DAY 2 PROGRESS: Diamond League is a lot harder for this deck than Platinum League, which has necessitated experimenting with some changes to the list. I tried a few variations that didn't stick briefly, and I'm 8-6 so far with the current version.

DAY 2 CONCLUSION: 48 games, with exactly a 50% Winrate at Diamond levels.

DAYS 3 & 4 CONCLUSION: Only 6 games, all losses. I'm getting really tired of bad RNG. Lightning Bolt, a newer inclusion, is near the bottom of the deck by the statistics, so I'm trying to think what would be good to replace it with. I feel like the deck needs some burst damage in addition to minions, since sometimes (mostly vs Priest) it just runs out of minions and hasn't killed the opponent yet.

Matchups

Demon Hunter: Tempo Demon Hunter is a fantastic matchup. They can't handle Scrapyard Colossi at all, unless they actually have (or generate) Consume Magic. Metamorphosis and Kayn Sunfury will do some significant face damage, but usually not enough. I don't have a good read on the Control Demon Hunter matchup yet, but it's probably a lot worse.

Druid: By far your best control matchup, you should usually win this no matter what kind of (meta) druid it is. They can't handle Scrapyard Colossi at all.

Hunter: About 50-50, maybe a little better. Just a question of whether you can stabilize fast enough.

Mage: Pretty challenging, but not impossible. Just be careful not to overextend into Poof, and hope that Reno backfires on them (at least to fatigue them eventually).

Paladin: Aggressive paladins are a pretty good matchup. Save an Earth Shock for Murgur Murgurgle. I don't have a good read yet on slower Libram Paladins.

Priest: Usually a loss, and usually a long, drawn-out, painful loss too. They can just eat all the damage the deck has to throw at them, and run you out of resources (and steal some of your best ones, e.g. with Soul Mirror or a Shadow Madness on your generated Reliquary of Souls. Can I rant for a moment here? HSReplay says that Priest should be only 10% of the meta at Diamond, but I've been running into it more like at least 25%, seriously, which has definitely worsened the deck's winrate. What luck! Anyway, I have occasionally beaten priests, but I'm not sure whether the better strategy is to rush them down quickly, or to try to outlast them in the fatigue/value game. Currently, I'm doing whichever is better facilitated by my draw.

Rogue: Pretty challenging, but not impossible. A lot depends on whether they destroy 3/7 of your minion power in one blow with Flik Skyshiv on a Muckmorphed minion; try to draw out Flik other ways if you can. Also, be careful about using Ancestral Spirits on things that could be Sapped or Blackjack Stunnered.

Shaman: Shamans are rare in the meta, but when they do happen they're pretty diverse, so I don't know how to play against them. Totem Shaman is the most common in my experience, and against that you can use standard anti-aggro tactics.

Warlock: Quest Warlock is a really bad matchup. Your early-game pressure isn't great compared to its removal. It can complete quest fairly early, then kill you with Malygos burn combos. I have won the matchup, but not often, and I haven't found a "secret" to doing so. I haven't faced Zoo enough times to have a good opinion about that matchup, but it's probably pretty good as most aggro matchups are, thanks to lots of AoE and so forth.

Warrior: I thought for a while the matchup with Bomb Warrior was impossible, but now I've managed to win it once by putting up a lot of taunts and fatiguing the warrior to death. They do draw a ton of cards with Battle Rage. Generating Reliquary of Souls was definitely a big help. Aggro pirate warrior is better, but still harder than most aggro matchups.

Changes Record

Witch's Brew and Rockbiter Weapon were performing too poorly, so I cut them, and with Rockbiter gone I cut Doomhammer as well.

In their places I'm trying out Lightning Bolt x2, Hex, and 2nd Earthquake. Feral Spirit instead of Hex was a consideration, but in general I've been doing better vs aggro than vs control, so I went with the card that should help more in control mirror matchups.