The hundreds of thousands of human soldiers and the millions of Leviathans kept killing each other, each side fueled by the mighty presence of their respective kings.
Thanks to the Leviathan King, the hive mind was able to mobilize the remainder of its army into a harrowing battle of attrition. Such a strategy meant the Leviathans killed far fewer humans each moment, but they could last significantly longer in the grand conflict. This approach was chosen because the hive mind believed the Leviathan King would surely win when it ultimately clashed with Vlad, the Xaos King.
All the Leviathan forces had to do was endure until Vlad fell. Afterward, the Leviathan King would direct its immense power against the rest of the human army, breaking every defensive line and formation, allowing the remaining Leviathans to swarm the humans and slaughter them all.