Myr Welder, Encroaching Mycosynth, Empowered Autogenerator, and Merrow Grimeblotter

Prerequisites

• Myr Welder on the battlefield
• Encroaching Mycosynth on the battlefield
• Empowered Autogenerator in exile
• Merrow Grimeblotter in exile
• Myr Welder does not have summoning sickness
• (at most) available

Steps

1. Activate Myr Welder using Empowered Autogenerator's ability by tapping it, putting a charge counter on Myr Welder and adding or for each charge counter on Myr Welder
2. Activate Myr Welder using Merrow Grimeblotter's ability by paying and untapping it, giving target creature -2/-0 until end of turn
3. Repeat

Results

• Infinite charge counters on Myr Welder
• Infinite colored mana