The demigod games

"Any ideas?" Zeus glanced around the throne room of Olympus "To be honest, our children our powerful, true, but I don't think our they are at the moment are powerful enough to defeat Gaea and the Giants. We need a way to hone their skills and find the best demigods of the generation."
"Why don't we ask bird brain, she seems to always know the answers," Apollo said, lying back absentmindedly in his throne. All eyes turned to Athena.
Athena cleared her throat. "Well, I don't even know if-"
She was cut off as an evil presence swept through the throne room. Her eyes glazed over, "What if we each sent two of our most powerful children to fight to the death, to weed out the weak ones?"
Zeus blinked, "Um, daughter, I'm not sure-". His eyes glazed over as well, and soon all of the gods in the room were staring ahead with blank eyes.
"So it's settled," Zeus stood up, "You have a day to pick your tributes, Hera shall be the game maker. Dismissed"