Jumbo Cactuar, and Fire Lord Ozai

Prerequisites

• Jumbo Cactuar on the battlefield
• Fire Lord Ozai on the battlefield

Steps

1. Declare Fire Lord Ozai and Jumbo Cactuar as attackers, triggering their abilities
2. Resolve the Jumbo Cactuar trigger, giving it +9999/+0 until end of turn
3. Resolve the Fire Lord Ozai trigger, causing you to sacrifice Jumbo Cactuar and add at least 10,000
4. Optionally, you can use this mana on Fire Lord Ozai's ability to exile each opponent's library and cast some of those cards without paying their mana costs

Results

• Exile each opponent's library
• Near-infinite red mana