Eidolon was making his move before Alexandria was even free.  He cast out a bubble that swelled as it moved through the air.  By the time it reached Echidna, it was twice as big around as she was, enough to reach from one sidewalk to the other.  The colors around her became muted, and her movements slowed to a tenth of the speed.

It was a time-distortion effect.

Wildbow, Worm, 19.5