Top-swap puts cards on top of your library. Theoretically if you could cast spells from the top of your library, you could continually cast the same Top Swap spell. So to imagine what that's like, here's a legendary creature that explicitly takes advantage of that.

In this space it means that if you can cast your Top Swap spell infinitely, you could keep filtering your deck until you get what you want in hand. Scary, and really does just combo off easily.

Whether this gives Top Swap or not, I want to test the boundaries of that. It should be a fun combo possibility, not an instant "I win" button, in the case of you having a Storm-Kiln Artist. Maybe this only lets you cast one spell per turn from the top?