The name “צְבָאוֹת-multitudes” refers to how Malchus of Atzilus descends into the created worlds of BY”A. There it creates “צְבָאוֹת-multitudes” of souls and angels, using the Keilim of the Sefiros of BY”A. (Similar, as it were, to how a person invests himself in creating thoughts, words, and actions.)
The Keilim of the Sefiros of BY”A are by themselves not “Elokus,” they are not fully bound up with the Infinite Light of Hashem as to be totally transparent to Hashem to the point that one only “sees” Hashem through them, as it were. This lack of unity between the Keilim of the Sefiros of BY”A and the Infinite Light is caused by the “Parsa-Curtain” that blocks off the Light of Hashem shining in Atzilus from entering BY”A. Because of this, the current state of the Keilim of BY”A is that they themselves are not Elokus directly, they are only a means through which Elokus functions to created souls, angels, and worlds etc. in BY”A.
Thus, the Keilim of BY”A are themselves also called “צְבָאוֹת-multitudes” of creations, since they are in the same general category as the multitudes that they create, in the sense that they are not directly Elokus.
However, the prophets had 1- souls of Atzilus, and 2- special power from Hashem that transcends Atzilus. Therefore, they had the power to “bypass” the “Parsa-Curtain” and bring down Hashem’s Infinite Light that shines in Atzilus to be fully revealed in the Keilim of BY”A, referred to as the “צְבָאוֹת -multitudes” and, by extension, into the multitudes of souls and angels that are bound up with the Keilim of BY”A through their service of Hashem. When that happens, Hashem is then referred to as “הֲוָיָ''ה צְבָאוֹת-Hashem, who is the Master of the Multitudes [of creations],” since, at that point, the Keilim of BY”A and the souls and angels connected with them become fully transparent to Hashem on the level of “Elokus,” and it is felt how Hashem Himself, as He is Infinite and Transcendent, is directly expressed in the reality of the Keilim of BY”A and the multitudes of beings that are bound up with him.
In other words, the name “הֲוָיָ''ה צְבָאוֹת-Hashem, who is the Master of the Multitudes [of creations],” represents the special accomplishment of the prophets, that they transformed the Keilim of BY”A into actual Elokus, and enabled a multitude of souls of the levels of BY”A to directly experience Elokus through Torah and Mitzvos.
In this sense, they didn’t add or take away anything from the Torah given by Moshe from Atzilus; they merely brought it down to the level of BY”A so that souls of people on that level can experience the Elokus of Torah and Mitzvos as they live in the physical word.
This is the meaning of the Name “צְּבָּאוֹּת” that is mentioned by the prophets:
