You control at least one additional creature with a +1/+1 counter on it.

Activate Ashnod's Altar by sacrificing another creature with a +1/+1 counter on it, adding .
The creature dies, triggering Basri's Lieutenant's second ability, creating a 2/2 Knight creature token.
When the Knight enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Knight.
Repeat.

You control at least one additional creature with a +1/+1 counter on it.

Activate Goblin Bombardment by sacrificing another creature with a +1/+1 counter on it.
The creature dies, triggering Basri's Lieutenant's second ability, creating a 2/2 Knight creature token.
When the Knight enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Knight.
Resolve the Goblin Bombardment ability from step 1, dealing 1 damage to any target.
Repeat.

You have a way to put a +1/+1 counter on a creature you control.

Put a +1/+1 counter on a creature you control.
Animation Module triggers, causing you to pay to create a 1/1 Servo artifact creature token.
When the Servo enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Servo.
Animation Module triggers, holding priority, activate Ashnod's Altar by sacrificing the Servo, adding .
Resolve the Animation Module trigger, causing you to pay to create a 1/1 Servo artifact creature token.
Repeat from step 3.

You control at least one additional creature with a +1/+1 counter on it.

Activate Phyrexian Altar by sacrificing another creature with a +1/+1 counter on it, adding one mana of any color.
The creature dies, triggering Basri's Lieutenant's second ability, creating a 2/2 Knight creature token.
When the Knight enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Knight.
Repeat.

You control at least one additional creature with a +1/+1 counter on it.

Activate Altar of Dementia by sacrificing another creature with a +1/+1 counter on it.
The creature dies, triggering Basri's Lieutenant's second ability, creating a 2/2 Knight creature token.
When the Knight enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Knight.
Resolve the Altar of Dementia ability from step 1, causing target player to mill cards equal to the sacrificed creature's power.
Repeat.

You have a way to put a +1/+1 counter on a creature you control.

Put a +1/+1 counter on a creature you control.
Animation Module triggers, causing you to pay to create a 1/1 Servo artifact creature token.
When the Servo enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Servo.
Animation Module triggers, holding priority, activate Phyrexian Altar by sacrificing the Servo, adding .
Resolve the Animation Module trigger, causing you to pay to create a 1/1 Servo artifact creature token.
Repeat from step 3.

You have a way to put a +1/+1 counter on a creature you control.

Put a +1/+1 counter on a creature you control.
Animation Module triggers, causing you to pay to create a 1/1 Servo artifact creature token.
When the Servo enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Servo.
Animation Module triggers, holding priority, activate Krark-Clan Ironworks by sacrificing the Servo, adding .
Resolve the Animation Module trigger, causing you to pay to create a 1/1 Servo artifact creature token.
Repeat from step 3.

Once you have infinite mana, you may forego sacrificing the creature tokens.

You have a way to put a +1/+1 counter on a creature you control.

Put a +1/+1 counter on a creature you control.
Animation Module triggers, causing you to pay to create a 1/1 Servo artifact creature token.
When the Servo enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Servo.
Animation Module triggers, holding priority, activate Thermopod's second ability by sacrificing the Servo, adding .
Resolve the Animation Module trigger, causing you to pay to create a 1/1 Servo artifact creature token.
Repeat from step 3.

You control at least one creature token with base power 2 or less.
Xavier Sal does not have summoning sickness.
There is a removable counter on a permanent you control.

Activate Xavier Sal by tapping it and removing a counter from a permanent you control, creating a copy of a creature token you control with base power 2 or less.
When the creature token enters the battlefield, Intruder Alarm and Serra Redeemer trigger.
Resolve the Intruder Alarm trigger, untapping all creatures.
Resolve the Serra Redeemer trigger, putting two +1/+1 counters on the creature token.
Repeat.