This spike of earth had come from behind the Death King and stabbed right up into its chest.
Since the Death King had been completely focused on Joan, it hadn't noticed this earth spike until it was too late.
As for why it was only focused on Joan, that was because it only took Joan as a threat.
There was nothing else that was here that it considered a threat, which was why it didn't pay any attention to the one that created the earth spike.
As for me, I was still holding up the Staff of Earth that I was pointing at the Death King.
That was because I injected more of my mana into the Staff of Earth to create two more earth spikes that suddenly came out from behind the Death King just like the first one. These two earth spikes were aimed right at the Death King's core like the first earth spike.
But in the end, they didn't reach it.
It wasn't that the Death King was able to gather its power to resist the earth spikes.