Just like when Kain first led his team to defeat Cecilia, what he did was control very minor elements, but those elements triggered a chain reaction, ultimately pushing Cecilia step by step towards defeat.
To Mera's question, Kain simply replied,
"Because I noticed. After entering that state, this person did nothing else besides using physical attacks and regeneration. Whereas if he truly mastered [Earth Magic], this battle would have been much harder."
"Meaning... that's his limit?"
"Exactly. He was pushed to his absolute limit, causing his perception of external factors to narrow significantly. Mera, you know that Magi need to be very focused when casting magic, right? And this guy had almost no breaks."
"Oh, I see."
Mera nodded in understanding.
The Final Showdown Looms
Meanwhile, while the two of them were still conversing leisurely, Faith's team had already eliminated Tolimus's team.