Added 'The Revenant'. — HellEscape Steam update #814186

The Revenant is a special hero that appears once you sacrifice a hero. He draws his special ability and skills from the heroes you sacrificed, and you can reroll his skill tree and ability whenever you choose to, and create your own unique builds. The other properties of the Revenant, like Health, Armor, and Speed, are the average of the heroes that were sacrificed.