There are two class challenges as part of The Spire. Druid, and Rogue.
The Druid Challenge puts you in with the boss – Netherspite.
Hearthstone Card Moonglade Portal
The card reads: Restore 6 Health. Summon a random 6-Cost minion.
Druid’s edition in the portal series of cards. It heals as you’d expect from Druid, and summons a random 6-cost minion which gives you the chance for some pretty decent minions.