They also heard her say, "You may think that you have trapped me, but that is not so. What you've done is to trap yourself with me. Better hope that I don't find you."
She was threatening them, and the three guardians took her threat seriously. So just like before, two guardians took action while the third one held on to the symbol of authority to keep it safe.
The guardian of earth and the guardian of fire took action on both the lava around them and the rock above them. They let the lava below them flow upwards into the cracks that she had created in the space that she was in. Then they made the lava cool within that space and turned it into rock.
They were filling up the space she was in with rock. This was to rob her of the freedom of movement and trap her within the rock.
This worked to great success, and the entire space was quickly filled up. This trapped her again, so she had to control the phantom giant to shrink to a third of its normal height.
