Reaper is a legendary major card out of the New mechanic pool. Shadowstep: a killing step refunds its whole cooldown, every time; damage 85%, cooldown 30% longer.

You can take it once · it only turns up when your Special ability can actually use it · it can be offered for 0 of the 34 abilities.

Only one card can reshape that ability this way — this one, or Void Rend and Ghost Step. Take one and the rest are gone for the run.