Rex, Cyber-Hound, Pili-Pala, and Alena, Kessig Trapper

Prerequisites

• Rex, Cyber-Hound on the battlefield
• Pili-Pala in exile
• Alena, Kessig Trapper in exile
• You had a creature with power 2 or greater enter the battlefield this turn
• Rex does not have summoning sickness
• Alena and Pili-Pala exiled with a brain counter on them

Steps

1. Activate Rex using Alena's ability by tapping it, adding at least
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