Encyclopedia of Mormonism pg. 380; “What Satan did not realize in Eden was that what he did in attempting to destroy the Father’s work was actually the very thing needed to fulfill the Father’s plan (Moses 4:6). People could not demonstrate their love of God and their willingness to do the work of righteousness sufficiently to qualify them for exaltation unless they were subject to, and able to overcome, evil and devil adversaries, such as Satan and his hosts (2Ne. 2:11-22).”
Rev. 20:10; “And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.”
This is so utterly disgusting. God doesn’t need anything much less evil from a fallen angel.