STRATEGY

The strength of Steel Sentinel lies on their immunity to attacks. The best way to remove his minions is to use effects like poisonous.

The main strategy is to buff poisonous minions such as Emperor Cobra with Power Word: Shield and Divine Spirit. A buffed Cobra can eliminate up to 4 enemy minions.

Other than that, you can use Jeweled Scarab and Tomb Spider to gain cards such as: Maexxna, Stampeding Kodo, Emperor Cobra (yes more Cobra), Mukla's Champion... (anything that buffs health or destroys a minion)

Please note that poisonous effect from Emperor Cobra / Maexxna cannot affect Divine Shield minions. That means you have to destroy their Divine Shield before using Cobra / Maexxna.

As the game progresses, you will slowly gain better minions from Entomb and Mind Control, while the boss will run out of minions and be defeated by fatigue. 

Overall, you can trade well and eliminate most of Steel Sentinel's minions. However, his armor is huge so always be prepared to fight a fatigue game.

A note of warning: The Steel Sentinel uses Brawl and Enter the Coliseum, which can clear all your board and your buffed minions. However, you will eventually have to sacrifice your good minions to those cards sooner or later. So don't be hesitate to buff your Emperor Cobra or play any other good card in early game. But don't go all-in. Keep a "plan B" on your hand in case bad things happen.

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OTHER CHOICES:

Other cards that could be added to the deck: Doomsayer, Big Game Hunter, Stampeding Kodo, Maexxna, Alexstrasza.