Death is coming for you… but all you can see is an ominous red cloud of smoke approaching you. Running is not an option, if you want to live you must brave your way into the smoke and destroy the red orb inside.
Wraith form creates a life drain aura around reaper, stealing life from nearby enemies and trapping the closest enemy. Shadow step creates a life drain explosion upon phasing out and phasing in, damaging nearby enemies and healing reaper. Ability damage and self-heal is increased when multiple enemies are hit.
Overwatch forum link with more details about the game mode and Reaper's abilities: