Guilty Conscience, Spiteful Sliver, and Indestructibility

Prerequisites

• Guilty Conscience on the battlefield
• Spiteful Sliver on the battlefield
• Indestructibility on the battlefield
• Indestructibility and Guilty Conscience attached to Spiteful Sliver
• Spiteful Sliver does not have summoning sickness

Steps

1. Attack with Spiteful Sliver
2. When Spiteful Sliver deals damage, Guilty Conscience triggers, dealing damage to Spiteful Sliver equal to the amount of damage Spiteful Sliver dealt
3. Spiteful Sliver triggers, dealing damage equal to the amount of damage Guilty Conscience dealt to it to target player or planeswalker
4. Repeat from step 2

Results

• Infinite damage