This clever loop is centered around Hinata, Dawn-Crowned, whose static ability reduces the cost of your spells by {1} for each target. Because Ghostly Flicker targets two permanents you control—in this case, Timeless Witness and a mana-producing land or artifact—Hinata's cost reduction completely offsets the spell's mana value, allowing you to cast it for a mere {U}. As Ghostly Flicker resolves, Timeless Witness enters the battlefield and its triggered ability immediately returns Ghostly Flicker right back to your hand. By looping this sequence indefinitely, you generate an endless storm count and trigger any enters-the-battlefield or leaves-the-battlefield effects your heart desires.