Howl

Heart of Rot – Free Update Chapter Embark on this side-story to the Capital, a city that long stood as a bastion of hope in a world overrun by howling beasts. The Prophet has heard rumors that the alchemists there have found a cure for the Howl. When she arrives, she finds a city consumed by rot ... Access to this update is FREE for anyone who has bought the Howl base game. You can access this update chapter from the Chapter 3 map at any point after reaching Chapter 3 of the main story. Heart of Rot follows its own storyline, and can be completed either before or after the main Howl story. This update features its own chapter map, new enemies, a new boss level, new environment mechanics, the new Lightning Shot skill (which, once unlocked, can be used in the main game!), and an NPC who fights by your side in later levels.

Source: Apple App Store listing.