Stones For Ammunition.

If he could eliminate his enemies early without any detriment, then he would have done so as soon as possible. None of the 100 of them would have left that hall because there was no rule against fighting in the assembly hall. 

The protection phase doesn't mean they can't sabotage each other though. That's why she attacked him. She wanted to interrupt the process of establishing his base so that he wouldn't be the first. 

She screamed at him, "Let go of me you weirdo."

Her head is in the ground so she can't speak with her mouth even if she has a mouth. What she is using to scream at him is her divine sense and it is very loud.

Unfortunately, loudness isn't going to deter him. He asked her as he pressed her head deeper into the ground, "Why are you calling me a weirdo?"

"You're weird because you're translucent. You look like cloudy glass instead of like white beautiful ceramic."