Kalu laughed wildly.
"What? Are you that eager to die by my hand? Old friend, I don't want to end your life so quickly."
The reason Kalu had not attacked with his full strength was precisely to stall for time and make Surtur's actions easier.
There was another concern as well. Loki had once told him that unless absolutely necessary, he could not kill The Ancient One, or someone would kill him too. Kalu had not believed it at the time and kept pressing him about who could possibly kill him.
But Loki had not said it outright, only vaguely telling him that it was some existence like a Creator God, someone Kalu could not afford to provoke. Kalu had been half-convinced and half-doubtful of Loki's warning.
But when it concerned his own life, he had no choice but to be cautious. Better to believe it than not.
Asgard, Bifrost. Heimdall stood there, guarding the Bifrost, his eyes capable of sensing all things.
With the sight of a thousand miles and ears that could hear the wind, he was observing the battle on Earth. He had personally sent two thousand Asgardian soldiers there, and as Asgard's guardian, he was quite worried about their safety.
Little did he know that while his attention was fixed on Earth, Surtur had already arrived at Asgard's gates, holding the massive flaming sword—the Twilight Sword.
Heimdall sensed Surtur's arrival immediately. Recalling his focus, he looked at Surtur by the gates and clenched his right hand. An unnamed divine sword appeared in his grasp.
"Surtur, you dare set foot on the soil of Asgard? You truly don't know whether you live or die."
Casually resting the Twilight Sword on his shoulder, Surtur continued forward with an indifferent expression, as if Heimdall did not exist.
Heimdall had