Unctus, Grand Metatect, The Watcher in the Water, and Mothdust Changeling

Prerequisites

• Unctus, Grand Metatect on the battlefield
• The Watcher in the Water on the battlefield
• Mothdust Changeling on the battlefield
• It is an opponent's turn

Steps

1. During an opponent's turn, activate Mothdust Changeling by tapping a blue creature you control except Unctus
2. The creature triggers, causing you to loot
3. The Watcher's first ability triggers, creating a 1/1 Tentacle creature token
4. Resolve the Mothdust Changeling ability
5. Repeat

Results

• Infinite self-discard triggers
• Near-infinite ETB
• Infinite draw triggers
• Infinite looting
• Near-infinite tapped creature tokens