Rex, Cyber-Hound, Pili-Pala, and Vhal, Candlekeep Researcher

Prerequisites

• Rex, Cyber-Hound on the battlefield
• Pili-Pala in exile
• Vhal, Candlekeep Researcher in exile

Steps

1. Activate Rex using Vhal's ability by tapping it, adding at least that cannot be spent to cast spells from your hand
2. Activate Rex using Pili-Pala's ability by paying and untapping it, adding one mana of any color
3. Repeat

Results

• Infinite colored mana
• Infinite colorless mana that cannot be spent to cast spells from your hand