Board Thread:General Discussion/@comment-6252544-20160213233306/@comment-26159109-20160214135606

Dues ex machina is not similar to Chekov's gun. It's quite the opposite actually, and it something that stories should use.

I'm not saying that OUAT does it all the time, especially in earlier seasons (true love potion, magic wardrobe, compass), but but they do it A LOT in later seasons (a potion Regina gave me, the blood of the people who wronged her most, a vial of magic).