The meaning of the blessing “Magen Avraham” in Shemoneh Esrei:
Since Avraham is Chesed, he needs a Magen/protector. From Avrahams Chesed everyone is good and holy and is given to live, even Kelipos. That is why Yishmael came from him. However this cannot be allowed, as then Kelipa will live forever, and in order for Moshiach to come Kelipa must eventually be wiped out. This is then the meaning of Magen Avraham, it serves as a guard that the Chesed does not give extra Yenika/nurture to the Kelipos.
 Torah Or Lech Licha 12a