It is a field for battle suspended between all worlds of existence, where all worlds may fight. The sky is perpetually bloodstained, as is the dead grass of the bumpy ground. Visibility is good, to a point; then sight fades away into the distance. This is where Ares has conducted and enjoyed many a bloody battle, stealing people from their dreams to fight here, or recruiting armies to fight more serious causes.
If you come here, you are here until Ares sets you free.
Or until you die.