Multicast was still an extremely difficult method to master because aside from the guaranteed first spell which the player could just use with ease, the other spells required the player to learn the movement and proper action.
Think of it as a person requiring to draw a square and circle at the same time.
It would be a snap of a finger if the person only needed to draw a square by itself. However, if they were told to draw two different shapes with both hands, the majority of the people would fail the assignment unless they had ample practice.
Of course, this was just a simple analogy. The Divine World required more extensive training and practicing to even begin multicast.
Therefore, Natasha's being capable of multicast 3 spells was extremely impressive.
Yet with just a single comment from Xu Feng, her spectacular achievement turned into a magical girl kid's show.
Even a saint would become infuriated by the blatant disrespect.