Still aspects unanswered, please see edit at bottom of post if interested.
The book Divine and Demonic in the Poetic Mythology of the Zohar (p. 247) discusses the concept of the "Other side" "capturing" and "enclothing" the "Holy." Some examples it gives are: the rabbinic dictum that "Tyre was only filled from the ruins of Jerusalem," (p. 245, foonoted: Ets Hayim, II, 57b. See Tishby, Torat Ha-Ra, 89), Lilit enclothing the Shechinah (p. 247, footnoted to Kin'at Hashem, 96), and a tradition transmitted by the Talmud that Jeroboam engraved divine names on the mouth of an idol, empowering it to speak (Sotah 47a, Sanhedrin 107b). The author then continues:
Luzzatto also declares that it was from this sort of dynamic that other arch- villains were able to derive their power, like Jesus and the “evil Armilus,” in both of whom the Messiah-son-of-Joseph was enclothed.
This is footnoted to Ramhal's Qin'ath Hashem (p. 104), https://www.hebrewbooks.org/pdfpager.aspx?req=51257&st=&pgnum=102&hilite=. The Hebrew is too difficult for me to parse. Can someone please explain the mechanics of this system of thought, and/or translate the relevant passages? Specifically I'm wondering: 1. why did MBJ's soul become enclothed in these arch-villains (i.e., maybe a Divine plan to destroy evil from within, a concept also discussed in Divine and Demonic? Maybe multiple reasons?), and 2. what dictates whether the 'enclothed' or the 'enclother' has agency (i.e. did MBJ's soul have any control over Yoshe's body and soul which "enclothed" it, or was it an inoperative prisoner or something in between)? Thank you. And also big thank you to @Deuteronomy and @Isaac Moses for helping me to edit down the question.
Edit: page 102 was linked by mistake, not 104, however, question seems to be addressed from page 102 to 105. I awarded one winning answer for summarizing page 102 about Joseph and Armilus, but still looking for answers about Joseph and Yoshke, and more mentioned here: Question about Joseph the Righteous, Yoshke, and Capture and Enclothing by the Sitra Ahra. If you're willing to translate those 4 pages, that would be the best answer, but I'm thankful for whatever answers ppl have time for!