Animation Module + Scion of the Swarm + Phyrexian Altar + Soul Warden

Animation Module

Scion of the Swarm

Phyrexian Altar

Soul Warden

How it works

1. Cause a creature to enter the battlefield under your control.
2. Soul Warden triggers, causing you to gain 1 life.
3. Scion of the Swarm triggers, putting a +1/+1 counter on itself.
4. Animation Module triggers, causing you to pay 1 to create a 1/1 Servo artifact creature token.
5. When the Servo enters the battlefield, Soul Warden triggers.
6. Holding priority, activate Phyrexian Altar by sacrificing the Servo, adding 1.
7. Resolve the Soul Warden trigger, causing you to gain 1 life.
8. Repeat from step 3.

This elegant little loop turns a single creature entering the battlefield into an unstoppable engine of growth and sacrifice. As soon as anything hits your board, Soul Warden rewards you with a point of life, which in turn causes Scion of the Swarm to grow larger with a fresh +1/+1 counter. That counter instantly wakes up Animation Module, letting you spend a mana to churn out a 1/1 Servo artifact creature token. Before that Servo's own arrival can disrupt the flow, you feed it directly to Phyrexian Altar to generate the exact mana you need to pay for Animation Module's trigger—keeping the cycle spinning endlessly while netting you infinite life and creature sacrifices.