Requires

Thrumming Stone must be on the battlefield. Memory Lapse must be in hand. Bonus Round must be in hand. Mana needed:

Steps

1. Cast Bonus Round by paying .
2. Thrumming Stone triggers, revealing the top four cards of your library and putting them on the bottom of your library.
3. Resolve Bonus Round, copying all instants and sorceries cast after it this turn.
4. Cast any other spell, or wait for an opponent to cast one.
5. Cast Memory Lapse by paying , targeting that spell.
6. Bonus Round and Thrumming Stone trigger.
7. Resolve the Bonus Round trigger, creating a copy of Memory Lapse, targeting the original Memory Lapse.
8. Resolve the copy of Memory Lapse, countering the original Memory Lapse and putting it on top of your library.
9. Resolve the Thrumming Stone trigger from step 6, revealing the top four cards of your library and casting Memory Lapse without paying its mana cost.
10. Repeat from step 6.

Results