Animation Module + Scion of the Swarm + Krark-Clan Ironworks + Soul Warden
Animation Module
Scion of the Swarm
Krark-Clan Ironworks
Soul Warden
Infinite +1/+1 counters on a creatureInfinite colorless manaInfinite creature tokensInfinite death triggersInfinite creature ETBInfinite lifegainInfinite lifegain triggersInfinite creature LTBInfinite creature sacrifice triggers
How it works
Cause a creature to enter the battlefield under your control.
Soul Warden triggers, causing you to gain 1 life.
Scion of the Swarm triggers, putting a +1/+1 counter on itself.
Animation Module triggers, causing you to pay 1 to create a 1/1 Servo artifact creature token.
When the Servo enters the battlefield, Soul Warden triggers.
Holding priority, activate Krark-Clan Ironworks by sacrificing the Servo, adding CC.
Resolve the Soul Warden trigger, causing you to gain 1 life.
Repeat from step 3.
This clever loop starts the moment any creature enters the battlefield, immediately setting off Soul Warden to grant you a drop of life. That life gain fuels Scion of the Swarm by growing it with a +1/+1 counter, which in turn wakes up Animation Module to offer a Servo token for a single mana. You can then feed that newly minted Servo directly to Krark-Clan Ironworks to generate the exact mana needed to sustain the loop while generating endless resources.