Kai had more blood at his disposal than he could ever hope to wield effectively. Gallons of it sprayed from the juggernaut's open wounds - deep, vicious slashes from Takeshi's blade, punctures from Sven's daggers, explosions tearing chunks out of its flesh.
But the blood was only as useful as the one commanding it.
And Kai instinctively knew he couldn't use it all. Not yet.
The way the blood responded to him, clung to him, he could feel its weight in his mind. A tether. A strain. Just like looking at a massive boulder and knowing you wouldn't be able to lift it, he understood his limits without needing to test them.
His power was growing fast, but it wasn't bottomless, as much as it felt that it was.
And even if he had infinite endurance, he simply didn't have the pure output to damage such a durable monster significantly.
So, for now, he played a more passive role.