Elemental Mastery, Steelfin Whale, and Encroaching Mycosynth

Prerequisites

• Elemental Mastery on the battlefield
• Steelfin Whale on the battlefield
• Encroaching Mycosynth on the battlefield
• Elemental Mastery attached to Steelfin Whale
• Steelfin Whale does not have summoning sickness

Steps

1. Activate Steelfin Whale by tapping it, creating a 1/1 Elemental creature token
2. The Elemental enters the battlefield as an artifact due to Encroaching Mycosynth, triggering Steelfin Whale, untapping Steelfin Whale
3. Repeat

Results

• Infinite creature tokens with haste
• Infinite ETB