The initial use of this card is pretty obvious: fill up the bag with blessings, and then play Ward of Protection at a cost of one fewer horror and one less resource. It also works on fellow investigators! The trade-offs are clear: it’s not automatic. But with favor of the sun, it becomes automatic*. With Tides of Fate, it becomes much more common; that card specifically lets you play it before drawing cards in the mythos phase. This card shines in support Mary or Mateo, where a lot of your game is spent filling the bags with goodness and protecting your fellow investigators.

(*Does "random" forbid this?)