Cast Time Stretch by paying its mana cost, causing you to take two extra turns after this one.
Move to your first extra turn.
Activate Mystic Sanctuary by tapping it, adding .
Cast Ghostly Flicker by paying 2, blinking Mystic Sanctuary and Mnemonic Wall.
When Mnemonic Wall and Mystic Sanctuary enter the battlefield, they trigger.
Resolve the Mnemonic Wall trigger, returning Ghostly Flicker from your graveyard to your hand.
Resolve the Mystic Sanctuary trigger, putting Time Stretch from your graveyard onto the top of your library.
Move to your next turn, drawing Time Stretch during your draw step.
Repeat.
This wondrous loop grants you infinite turns by endlessly recycling your most powerful spells right out of the graveyard. It all begins when you cast Time Stretch to claim two extra turns, which gives you all the time you need to set up your engine. By using Ghostly Flicker, you can repeatedly blink both Mystic Sanctuary and Mnemonic Wall simultaneously. Each time they return to the battlefield, Mnemonic Wall's entry trigger plucks Ghostly Flicker right back out of your graveyard, while Mystic Sanctuary's landfall ability places Time Stretch squarely on top of your library, ready to be drawn and cast anew on your next turn.