"!!!" The King Class Monsters around him were dumbstruck. The attacks and Felix's sudden change had confused them and stopped them from hindering Felix, but they never expected that one opportunity was all it took for Felix to help someone from another battlefield without sacrificing anything.
After that attack, Rea would surely gain an advantage over the King Class Monsters she had to face.
One of the Four King Class Monsters could exchange their position to balance it, but there was no way Felix allowed them to do it. Felix could see their reaction and movement clearly after the change, and their monster's instinct was telling them that Felix had a complete grasp of their movement. Pulling any trick would simply give Felix an opportunity to strike.
The Four King Class Monsters knew they had to kill Felix as quickly as possible or Rea would have killed the ones she faced first.
But they didn't know whether they could kill Felix or not.