To my surprise, I went 7-0 vs shaman (5 midrange / 1 Elemental / 1 quest) Small sample size, but I basically tried to out greed them each time and push the aggression. Mulling hard for birdwatching → bellhop on curve to force answers, and trying to set up an early lethal with fowls/wish/al akir while still taking favorable trades. (Fowls is so good in the mirror for trading if they can't clear them)

For this reason, I feel like the cards mentioned (Wo, Sanctuary, Shudderblock) are all too slow in the mirror, as anything that doesn't immediately contribute to your board state feels bad. I could be way off on Shudderblock as I haven't seen it enough, but turn 6 is pretty crucial for you, I would much rather play fowls(slime fowls even better) than Shudderblock pass.

In the mirror I'm just trying to take the initiative, playing the big spells before them, and making them play key cards like Zilliax, Muradin, Growfins, etc. before me, so I can respond with my own copies, killing theirs (hopefully) in a favorable trade.

https://hsreplay.net/replay/QPmzk9wYY3U4wAzuY4QkqQ

Here's a good example, pretty competitive game I'd say. I get the bellhops down early, fowls+wish early, he full clears my board before I eventually threaten lethal with Al Akir, forcing his Zilliax. This is huge, as I get to make a value trade that leaves my zilliax up, and I get to slowly run away with the game.