When Farmer Cotton enters the battlefield, it triggers, creating at least four 1/1 Halfling creature tokens and four Food tokens.
Activate Farmer Cotton, four Halflings and four Foods by tapping them, adding 6.
Activate Meticulous Excavation by paying 2, returning Farmer Cotton from the battlefield to your hand.
Repeat.
This loop takes flight by casting Farmer Cotton to flood your board with a generous harvest of Halflings and Food tokens. Thanks to A Realm Reborn, every single one of those new permanents gains the ability to tap for any color of mana, funding the rescue mission. You simply use Meticulous Excavation to bounce Farmer Cotton back to your hand for reuse, keeping the cycle spinning as long as you have the mana to spare. With Frostcliff Siege chosen for Temur, your massive army of tokens even gains haste and trample to immediately overwhelm your opponents, turning an endless loop into a decisive victory.