The Bowl of Bones is an arena where Silver and Red criminals are executed. Holding cells are made of Silent Stone, and the arena has seats for an audience to hide behind an electric shield.
The Poison Bride
After an animos from House Viper sent dozens of venomous snakes into her husband's bed, she was executed in the Bowl of Bones for her crimes. She was then nicknamed the Poison Bride.
The Great Greco
The Great Greco has only been mentioned, but is implied they were a strongarm that ripped open bodies and feasted on their internal organs.
Cal and Mare
After Elara Merandus controlled Cal to kill Tiberias Calore VI, Maven Calore sentenced Cal and Mare to death for treason. Maven came to their holding cell privately and asked Mare if she was willing to be his bride, in exchange for freedom. Mare ultimately chooses to die than become Maven's Red Queen.
Mare and Cal are dragged to the gates by Rane Arven and watch Mare's guard, Lucas Samos, be executed right in front of them. Mare and Cal are then dragged into the sandy arena, Cal able to use his fire powers, but Mare completely silenced by Arven. Five executioners then walk into the arena: Lord Osanos, Stralian Haven, Ryker Rhambos, and the two magnetrons Ptolemus and Evangeline Samos.
Still silenced, Mare must use her bare wit. Maven cheats, opening a chasm under the arena for Lord Osanos to bring water out of. While the magnetrons team up on Cal, the Haven executioner holds Mare by her neck and tries to choke her. This fails, and the Haven executioner soon dies. The Rhambos strongarm throws a metal pipe at Mare, but she ducks, and it hits Arven straight through the chest, scraping Mare's cheek in the process. The video screens turn off and the audience is evacuated, but everyone has already seen: a Red with Silver abilities.
Freed, Mare instantly electrocutes Ryker Rhambos and moves on to Cal almost dying. Lord Osanos has Cal surrounded in a water bubble with the magnetrons surrounding him. Mare electrocutes the water, zapping Osanos and making him take his aim off Cal. Cal is freed from the water, and the two fight the magnetrons. Mare on Evangeline, Cal on Ptolemus.
Cal and Ptolemus brawl, the tide shifting every few minutes, while Lord Osanos wakes up and tries to use electricity on Mare. Mare electrocutes the water, frying Osanos, as the water seeps back into the sand of the arena. Cal pins down Ptolemus, but Maven interrupts and hundreds of Security, Sentinels, and soldiers surround them.
Mare uses the electric shield to her advantage, breaking it and sending bolts of electricity onto the guards. The Security soldiers run for the gates, as well as Ptolemus and Evangeline, but the soldiers and Sentinels still stand.
Finally, Mare and Cal are pulled into the chasm which used to hold Lord Osanos's water by the Scarlet Guard and escape the Bowl of Bones.