A stadium built by King Taron in Sabek that hosts gladiatorial games for the entertainment of the nobles.

At the arena, you are greeted by a shocking scene. Smoke rises through a massive hole in its side. All the nearby vendor carts have been destroyed, and several mangled bodies lie in the rubble. - Eye of Ulos (RPA-ADV4) 

An explosion is set off by Rose as a distraction for the King's Guard while the Starlit Door advances their plot.

Taron's Arena was built after a trip the king made to the Colosseum of Ashes;

Taron’s arena vanishes and is replaced by a colosseum from some other world. The crowd roars within. You see a young King Taron emerging from the front gate, clearly pleased with what he’s seen within. - Eye of Ulos (RPA-ADV4)

It is not uncommon for the gladiators that fight in the games to be from Kulbak Prison:

Hardened in Kulbak among the Blackwing Raiders and then Taron’s arena, the Kobolds outmaneuver you and drive you away. - Tome of Encounters (RPA-ADV4)

Upon arrival at the Arena you must decide which threat to attend to:

• Assist Zalic in confronting the Ogre:
  • Attack the Dragul:
    • Succeed, and slay it efficiently.
    • Fail, and the Ogre fights you back, continuing toward the palace.
  • Attempt to talk it down:
    • Succeed, and win favor with it as you promise safe passage out of the city.
    • Fail, and have no choice but to defend yourself.
  • Side with it and attempt to sabotage your commander:
    • Succeed, and the Ogre gets away, Zalic seething at your betrayal.
    • Fail, and Zalic dispatches the Ogre no thanks to you.
• Protect the citizens of Sabek from a gang of Goblins:
  • Attack the Dragul:
    • Succeed, and exterminate them, reconvening with a wounded Zalic.
    • Fail, and they run further toward the palace.
  • Convince them their friend is dead:
    • Succeed, and they move on.
    • Fail, and they pelt you with rubble.
  • Help them uncover their buried friend:
    • Succeed, and they continue with their friend in tow.
    • Fail, and they mourn the loss of their brethren, scared off by Zalic.

However, if you went to the Temple of Ulos first instead, you will find Zalic buried beneath rubble from the explosion:

• Attempt to free him:
  • Succeed, and cement your loyalty to the King's Guard.
  • Fail, and Zalic will breathe his last breath, crestfallen that you were not here to suppress the mounted attack.
• Let him die, with his final look at you being one filled with horror.

As you leave the Arena, you find a most curious shard of glass.

Inspecting the wreckage with the focusing lens, you come to find it was set off by bluestone powder;

You inspect the rubble with your focusing lens and discover a residue of blue powder. - Eye of Ulos (RPA-ADV4)

A Cyclops bursts from Taron's Arena and rampages toward an Elf child, whose father drops a scroll bearing your mark, rolling into a fire:

• Usher out and save the civilians, and the father will reward you with the scroll;

“Use it, Child of Fate,” he says. “Choose the end of your story.” - Elf father, Backstory Codex - Chosen One (RPA-BC)

• Grab the scroll, and leave with destiny in your mind and retribution in your heart.