Lethal Vapors, and Sorcerous Spyglass

Prerequisites

• Lethal Vapors on the battlefield
• Sorcerous Spyglass on the battlefield
• "Lethal Vapors" chosen with Sorcerous Spyglass

Steps

1. Whenever a creature enters the battlefield, Lethal Vapors triggers, destroying that creature
2. Because Sorcerous Spyglass prevents Lethal Vapors's activated ability from being activated, it cannot be destroyed due to its ability

Results

• Destroy all creatures that enter the battlefield