Kronos - Powers are Limited

Thalia shrugged. “We’ve sealed off the subway tunnels into Manhattan. My best trappers took care of it. Also, it seems like the enemy is waiting for tonight to attack. I think Luke”—she caught herself—“I mean Kronos needs time to regenerate after each fight. He’s still not comfortable with his new form. It’s taking a lot of his power to slow time around the city.”
Grover nodded. “Most of his forces are more powerful at night, too. But they’ll be back after sundown.”

***

The Last Olympian, Chapter 12