Shovel Knight: Plague of Shadows is the second campaign of Shovel Knight and an alternate story to Shovel of Hope. It stars the mad alchemist Plague Knight in his quest to craft the Serum Supernus, the Ultimate Potion, from the Essences of his fellow knights of the Order of No Quarter. The campaign adds new related Feats and initially introduced Challenge Mode for both Shovel Knight and Plague Knight. Plague of Shadows was released on Sep 17 2015 as a free expansion to Shovel Knight. (wikia.com