Heroic Magic Mirror Pacifier
IMPORTANT: Does not work in Normal! This strategy relies upon the Magic Mirror's Heroic Hero Power. The boss is very different between Normal and Heroic modes. Please check other decks if you are seeking a guide for Normal mode.
Stall the Magic Mirror's onslaught with minions that can't attack! Playing a card like Ancient Watcher will fill his board with useless minions, eventually choking out his 7 minion limit. Use other spells and cards to stall and deal with his minion spam, and you will eventually block off future minions from the board. Once his board is closed off, just stall until fatigue or use silenced minions to take him down.
Mulligan for cards you can play early, primarily Argent Watchman, Ancient Watcher, Shadow Word: Pain, and Holy Smite. Do not mulligan for Silence, Sunfury Protector, or Convert. These are combo pieces that are nice to have with their counterparts, but alone do not further your gameplan. You'll want to drop passive "Can't attack" minions as soon as possible to fill up the Magic Mirror's board. Argent Watchman is one of the best cards, since you'll find yourself using Lesser Heal often and will let you remove the majority of his early minions. Try to save your removal for turns where you can remove a minion AND play a passive minion to replace it. Argent Watchman or a silenced/taunted Ancient Watcher/Silithid Swarmer/Eerie Statue will typically clear the board of active minions. Convert is used on the passive minions you've placed on his board for better redundancy on passive minions. His bigger minions at this point are Flamewaker and Mana Wyrm, so deal with those when you can. Sometimes you'll take a nasty +3 or +4 spell damage AoE on your minions, but just stall until you can fill in more spots with passive minions. If you used Power Word: Glory early, it's okay to kill the minion if it's dangerous or if you can replace it immediately.
Usually, the Magic Mirror has about 2 or 3 spots for his own minions later in the game. Always try to remove one and play a new passive minion to replace it. Save Entomb and Shadow Word: Death for Archmage Antonidas and Rhonin, but don't be afraid to use them on a powerful Mana Wyrm. Also, always test his secrets as soon as they're played. He has Duplicate, Mirror Entity, and Counterspell. Test Duplicate on Bloodmage Thalnos or Sorcerer's Apprentice. If you're certain it's Duplicate, try it on a passive minion and see if he'll play them onto his own board. Against Mirror Entity, try to land a double helping of passive minion. Counterspell is difficult to deal with, just make sure it's gone when you suspect Archmage Antonidas or Rhonin are about to be played so you can comfortably remove them. You can use Power Word: Glory at this stage to heal more damage than you take. As long as he can't kill his own minions on yours, you can stall the game out to fatigue or win using silenced minions.
- Consider running 2 copies of Power Word: Glory, perhaps instead of 2 Shadow Word: Death or Entomb.
- Use 0 attack minions that benefit you in some way, such as Lightwell or Lightspawn. These will be 1/1 minions for the Magic Mirror, but you can silence them back into 0/5 minions.
- If you need extra healing, there is space for Zombie Chow, Corrupted Healbot, or Cult Apothecary. You can probably replace taunt providers, like Defender of Argus, with these. Zombie Chow is also good for early game control, so it's the strongest option of these cards.
- I've yet to draw to Cyclopian Horror in my testing for this. I assume it's always going to be a 3/10 by turn 4, so I'd like to know if it serves anyone well.
- To be completely honest, Purify actually has a space in this deck. Using Silence to enable Ancient Watcher or Eerie Statue doesn't feel great because it doesn't replace itself and you can usually afford an extra 2 mana. When it's released, I'd consider Purify over Silence.
Like any deck in heroic, it may take a few tries to get a good mulligan or overcome the enemy's power plays. Keep in mind this deck is NOT designed to go face or generate tempo using silenced "Can't attack" minions on your board. Good luck, have fun.