Jamieson, Fausset and Brown on Jeremiah 30:16

16. Therefore--connected with Jr 30:13, because "There is none to plead thy cause ... therefore" I will plead thy cause, and heal thy wound, by overwhelming thy foes. This fifteenth verse is inserted to amplify what was said at the close of Jr 30:14. When the false ways of peace, suggested by the so-called prophets, had only ended in the people's irremediable ruin, the true prophet comes forward to announce the grace of God as bestowing repentance and healing.

devour thee ... be devoured ... spoil ... be a spoil ... prey upon ... give for a prey--retribution in kind (see on Jr 2:3; Ex 23:22; Is 33:1).