Entreat the Angels seems like a pretty sweet card, but I don't see where they fit? I've scrounged around on the internet a bit and there doesn't seem to be much of a strategy or deck that does along with it.

Look at the legacy deck called "miracles." They don't usually run very many copies of entreat, but they have sensei's tops and brainstorms to help set-up the entreats and terminus(es?) they run.

Its also pretty wicked in EDH.