Rashi on TanakhJeremiah 21

Behold I turn back the weapons of war There are some among you who know how to adjure the heavenly princes in charge of retribution, that each one save them from the evil he is in charge of, and you rely on that. Behold, I will transfer one’s authority to another one, and you will not know whom to adjure.

and I will gather them i.e., the weapons of war, into this city, that I will destroy you with pestilence through the angel of death, who is one of the heavenly princes. And in this manner it is explained in the chapter (v. 6): “with a great pestilence they shall die.”

and he will have his life as a prey As a man who plunders booty, and he seizes and goes away, so will his life be plundered from death by the slayers.

My anger as the Targum, רוּגְזִי My anger.

from the hand of the robber Its accent is below for it is not a noun but a noun denoting the robber who robs others.

with no one to extinguish [it] that no one of you will escape as a survivor.

O dweller of the valley Jerusalem is in the midst of a valley. Another explanation. That the Holy One, blessed be He, devised a deep plot against you to destroy you.

rock of the plain Mountain, entirely surrounded by plain.

Who will encamp upon us who will encamp upon us. Comp. (II Kings 6: 9) “For there the Arameans are encamped (נְחִתִּים).”