Capítulo 490: We Need A Plan

Luna didn't use her control ability when she was fighting against that elder Eldritch. She knew that the monster was far stronger than her, so she wouldn't be able to hold it for even three seconds before it broke out from her control and the amount of time needed to activate the ability would have given the Elder Eldritch an upper hand. Luna could only do it here because she had gotten stronger after she started training seriously again. 

But now that two of the Eldritch were dead and there was only one Elder Eldritch remaining, along with the calamity classes and Sasha, Luna knew they could win this. Luna had more than enough mana as far as she was concerned. She just had to get some of her stamina back, and then she would be able to continue fighting.