Curse of Naxxramas was the Hearthstone solo content expansion. I’m still working my way through it. When it was first released, players could unlock the different wings with either gold or real world currency. I chose gold.
The third boss in the Plague Quarter of Naxxramas is Loatheb. Before players can fight Loatheb, they have to beat the previous two bosses in the Plague Quarter: Noth the Plaguebringer and Heigan the Unclean.
It took me two tries to defeat Loatheb. The screenshots you see in this blog were taken on November 9, 2015.