The Ooze, Grimgrin, Corpse-Born, Combine Guildmage, and March of the Machines

Prerequisites

• The Ooze on the battlefield
• Grimgrin, Corpse-Born on the battlefield
• Combine Guildmage on the battlefield
• March of the Machines on the battlefield
• available

Steps

1. Activate Combine Guildmage's first ability by paying and tapping it, causing each creature you control to enter with an additional +1/+1 counter this turn
2. Activate Grimgrin by sacrificing a creature with a +1/+1 counter on it
3. When that creature dies, The Ooze triggers, creating a Mutagen artifact token for each +1/+1 counter on the sacrificed creature
4. These artifacts are also 0/0 creatures due to March of the Machines
5. Each Mutagen artifact creature token enters with at least one +1/+1 counter on it due to Combine Guildmage
6. Resolve the Grimgrin ability, untapping it and putting a +1/+1 counter on it
7. Repeat from step 2

Results

• Infinite +1/+1 counters on a creature
• Infinite artifact ETB
• Infinite artifact LTB
• Infinite artifact sacrifice triggers
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers