There are two class challenges as part of The Spire. Druid, and Rogue.
The Rogue Challenge puts you in with the boss – Shade of Aran.
Hearthstone Card Ethereal Peddler
The card reads: Battlecry: Reduce the Cost of cards in your hand from other classes by (2).
Time to work on those burgle decks. 2 mana can be game changing on the right cards, it’s still RNG heavy what cards you will get but I think this is a decent card that will see play in the right decks.