When Hope saw Mika charging towards the last bats, he immediately sensed that something was wrong. After all, none of these bats had used the dark element, even though they all possessed it.
And when he saw that, indeed, just as Mika was about to engage in combat with them, the area around them turned pitch black, Hope didn't even hesitate. Without moving from where he was, he extended his hands forward and beams of white light shot out from each of them.
Alanis could have prevented him from acting and let Mika fight alone, like he wished too, but when he saw him being engulfed by this sudden surge of dark element, the fear that Mika could be harmed, even by a mentally attack, was too strong.
He felt a great relief when Hope decided to use the light element to counter this attack because he knew that Mika would never be mad at their son if he chose to help him out.