He heard the gentle splash of water before he saw the warrior touch down. 

He got up from his perch and readied his rifle as he saw the warrior appear from seemed to be nowhere. Immediately his brain tagged the newcomer as not being a Viking; the armour was completely different. Something was familiar about her though, the way her armour looked, the way she held her spear. Cho knew where she was from immediately, without having to consult any technology. 

A Spartan. She was a Spartan.

[i]Thank you 300.[/i]

He slowly advanced forward as she dropped to a crouch and scanned the area, rifle down but at the ready. 

In the center of the arena, the plinth began to glow. A small monolith soundlessly rose from its core, polished white marble and intricate carvings. From within this monolith sprang an immense forcefield that encircled the area, glowing a faint blue before it disappeared from view. No doubt its invisibility was meant to keep the aesthetic of the arena itself. 

Cho kept an eye on the warrior. Something told him this Spartan was dangerous as Kolskegg was. Warily he stepped closer, raising a hand in greeting. 

"Hail, stranger. Were you drawn here as well?"