The Normal Chess event replaces your hero class with the White King, thus you aren’t able to choose a deck. Instead, you are given random cards based on the chess pieces for this particular encounter. This is a very unique encounter in the Hearthstone: One Night in Karazhan adventure.
The Black King’s Hero power is Cheat: Destroy the left-most enemy minion. Try to have White Pawns to the left-most to avoid getting important cards killed right off.
At the end of your turn, all your cards deal damage to the enemy cards in the opposite side. Depending how you position your cards, a card can attack two enemy cards.
These are the cards you get (to the left), and the cards the Black King plays (to the right):
Magic Mirror is the second boss in the Parlor wing. His hero power allows him to duplicate minions you summon and those he summons. If you play as a Mage, in addition to Deathrattle minions, you should add Flamewaker, Knife Juggler, Chrommagus and Sorcerer Apprentice are good choices to get duplicated by his hero power.
Paladin decks can easily take this boss, especially with Chrommagus and a bunch of deathrattle minions in the mix.
Location: The Parlor Passive Hero Power: Whenever a minion is played, summon a 1/1 copy of it.
Silverware Golem is the first boss in the Parlor in the One Night in Karazhan adventure. The key to beating him is to deal immediately with Cup and Knife (5/1). Destroying Knife removes the Taunt from its minions. The ideal class to fight him is Mage.