It works when you have Nether Void, Possibility Storm, or similar in play. Take P-Storm for example; first, you cast an artifact from your hand, stacking Mishra's trigger underneath P-Storm's. You let the P-Storm trigger resolve; you get a free artifact from your library, and whatever artifact you just cast is now at the bottom of your library. Now when Mishra's trigger resolves you can go fin the artifact with the same name sitting at the bottom of your library. While your opponents can't cast anything hen they want to cast it, you get to cast two spells for the price of one.
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