There and Back Again, Blade of Shared Souls, Flamewright, and Umbral Mantle

Prerequisites

• There and Back Again on the battlefield
• Blade of Shared Souls on the battlefield
• Flamewright on the battlefield
• Umbral Mantle on the battlefield
• There and Back Again has exactly two lore counters on it
• Flamewright does not have summoning sickness
• Umbral Mantle attached to Flamewright
• available

Steps

1. At the beginning of your precombat main phase, There and Back Again triggers, putting a lore counter on it
2. There and Back Again's third chapter ability triggers, creating a legendary 6/6 Smaug creature token and causing you to sacrifice There and Back Again
3. Activate Flamewright's first ability by paying and tapping it, creating a 1/1 Construct creature token
4. Activate Blade of Shared Souls' equip ability by paying , attaching it to the Construct token
5. Blade of Shared Souls triggers, causing the Construct to become a copy of Smaug for as long as Blade of Shared Souls is attached to it
6. Put the Construct token into your graveyard due to the legend rule
7. When the Construct dies, it triggers, creating fourteen Treasure artifact tokens
8. Activate six Treasures by tapping and sacrificing them, adding
9. Activate Flamewright by paying and untapping it, giving itself +2/+2 until end of turn
10. Repeat from step 3
11. Once you have infinite mana, you may simply tap and untap Flamewright to get infinite Construct tokens, and then use its second ability to sacrifice them for infinite damage

Results

• Infinite colored mana
• Infinite creature tokens
• Infinite damage
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinitely large Flamewright until end of turn
• Infinite Treasure tokens
• Infinite untap of nontoken creatures you control
• Infinite mana nontoken creatures you control can produce
• Infinitely large nontoken creatures you control