Sitra Ahra aka סטרא אחרא (in Aramantic) aka Sitra Achra aka The Dark Side of the Tree of Life aka the קליפה Qlipoth aka the "Peels", "Shells" or "Husks of the Tree left over after the Tzim Tzum Breaking of the Vessels, where Sparks of God's LIGHT get mired in mud; of the 10 Sepheria of the Obverse of the Tree of Life, the Other Side, only 7 of the Evil Sepheria could endure, and they were guarded by Ashmedai (whose name comes from an early Zoroastrian Devil), Taninniver, the blind dragon, Sammael, the Angel of Death* and Sammael’s wife Lilith… the top 3 Sepheroth have no Evil twins, and neither do Geburah and Gedulah, it seems; The components or the Sepherah of God, Nature and Man when unbalanced and out of control; Called the Temurot or thorns from a Date tree by David ben Yehudah he-Hasid
Bill Heidrick says Thamiel= Duality in God, Chaigidel= Confusion of the Power of God, Sathariel= concealment of God, Gamchicoth= Devourers, Golachab= Burning Bodies, Thagirion(n)= Those Who Bellow Grief and Tears, Harab Serapel= Ravens of the Burning of God, Samael= The Desolation of God, or The Left Hand, Gamaliel= Polluted of God, Nehemoth- Whisperers aka Night Specter;
The desire to do Good and Evil is inbred in Humanity, with yetzer hara יֵצֶר הַרַע aka Evil Inclination one of the Temptations to be resisted.
Teachers: Moses Zinfa of Burgos; Moses ben Jacob Cordovero; Eleazar Ben Judah ; Ya’akov Hakohen aka aka Jacob HaCohen; David ben Yehudah he-Hasid; Kenneth Grant;Christan Knorr von Rosenroth; Aleister Crowley; Dr. Israel Regardie; Bill Heidrick of the OTO; Don Karr; Robert A. Johnson;
- The Angel of Death comes in many forms, "The destroyer" aka"ha-mashḥit"(Ex. xii. 23), and the "destroying angel" aka "mal'ak ha-mashḥit" or mal'ake ha-mawet are terrible, but understandable, while Sammael brings unfair Death and Azrael was the Comforting Angel of Release from pain and suffering.
Resouirces: http://en.wikipedia.org/wiki/Qliphoth ; http://en.wikipedia.org/wiki/Yetzer_hara; https://archive.org/stream/LeftHandPath666-2015/248111509-Edgar-Kerval-Various-Authors-Qliphoth-Opus-III_djvu.txt ;