The Firesoul Phantom of Keystone Tower

From the introduction:

You feel the immense heat on your skin, beads of sweat already rolling down your spine, and then it appears, wreathed in flames, its face expressionless, distant, alien. Its two ember eyes focus on something on the ground. The phantom's ghastly form floats through the air, extending its spectral hand towards your companion's unconscious body, lying motionless on the floor. Your ears are filled with the roar of the fire and the rhythmic thrumming of the arcane mechanism in the center of the room, like the beating heart of a leviathan that swallowed you all whole. The infernal specter's hand reaches your friend's body and her skin begins to blacken. Moments later it becomes harder to even remember her name...