Standard Osiris Open rules apply. It's up to you to say how the magic of the arches work.
If the legends of them are true.
Standing out as a legend to a time long past, when gladiators fought for their lives all for the glory of the empire, the Four Horsemen Hellhole waits in the Jagged Mountains. As true as an arena as it could be called it is a huge ellipse, reaching a five hundred feet at its largest length and two and fifty hundred feet across at the greatest width. A thirty foot high, granite wall runs around the perimeter of the oval field, designed once to keep all the gladiators in, and protect those without. For those spectators a hundred rows of heavy stone benches waited, arching out like an ampitheatre, with entrances available as holes that led up from the access tunnels.
Time had passed, however, and much of the elaborate, carved facade on the outside of the arena, once depicting the brave lives of the gladiators, had fallen to nothing. Even parts of the many tiered seating had begun to crumble, smashing into one side of the field's wall and making there a direct access to the seating that the viewers would have found fearful. The field itself had a large chunk missing, now, the floor fallen in over time to reveal the labyrinth of pens and cells beneath that once had held the fighters - until it was there time to die.
But some things had not gone. Some form of ancient, unknown magic, it is said, kept the four arches that opened onto the battlefield intact. Carved into these arches are horses - one mighty steed for each - and a word on each one. Starting from the north arch they read:
War. Pestilence. Famine. Death.
Nobody had gone near these gates for many years. If you want to explore the ruins - why you just come up through the now broken floor. Because in through those archways voices could be heard - screaming, crying and drowning at times. Suffering. Stories spoke to say that if you came within ten foot of the fearsome stone horses that terrible things would happen. That war, or pestilence, or famine or death themselves would come themselves and try to kill you.
Riding on their dire horses.