This prayer is said after the first Trumpet Blasts on Rosh HaShana.
The Sefer HaChesheq 24 says: Do not think in your hearts during this prayer that because he is associated with great power the Sar HaPanim is a A god(ie alongside HaShem). Only HaShem is a god and (unique) God as well as a king(unique) King (there is no King Messiah but HaShem). MemTet is an extension of HaShem's Will.