Sensei's Voltaic ParadoxParadox Engine Buy + Voltaic Key Buy + Sensei's Divining Top Buy
In addition to the cards listed, a nonland permanent that can produce at least 2 mana is also needed for this to work.
After dropping all 3, along with the mana rock, activate Top and hold priority. Then float mana with your rock(s) and activate Key to untap Top. Finally, activate Top again with the original Top activation still on the stack.
This'll put Top back into hand along with the top card.
Finally, recast top and restart the loop.
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