Protean Thaumaturge, and Ondu Spiritdancer

Prerequisites

• Protean Thaumaturge on the battlefield
• Ondu Spiritdancer on the battlefield

Steps

1. Cast any enchantment by paying its mana cost
2. When the enchantment enters the bttlefield, Protean Thaumaturge and Ondu Spiritdancer triggers
3. Resolve the Protean Thaumaturge trigger, causing it to become a copy of Ondu Spiritdancer while keeping its ability
4. Resolve the Ondu Spiritdancer trigger, creating a token copy of the enchantment that was cast
5. When the enchantment enters the battlefield, Protean Thaumaturge triggers twice
6. Resolve the first trigger, causing it to become a copy of Ondu Spiritdancer while keeping its ability
7. Resolve the second trigger, creating a token copy of the enchantment that was cast
8. Repeat from step 5

Results

• Infinite copies of the cast enchantment