Cause a creature to enter the battlefield under your control.
Ajani's Welcome triggers, causing you to gain 1 life.
Karlov triggers, putting two +1/+1 counters on itself.
Animation Module triggers, causing you to pay {1} to create a 1/1 Servo artifact creature token.
The Servo enters the battlefield, triggering Ajani's Welcome.
Holding priority, activate Ashnod's Altar by sacrificing the Servo, adding {C}{C}.
Resolve the Ajani's Welcome trigger, causing you to gain 1 life.
Repeat from step 3.

Infinite +1/+1 counters on a creature

Infinite colorless mana

Infinite creature tokens

Infinite death triggers

Infinite creature ETB

Infinite lifegain

Infinite lifegain triggers

Infinite creature LTB

Infinite creature sacrifice triggers

Karlov of the Ghost Council

Animation Module

Ajani's Welcome

Ashnod's Altar

Activate Karlov of the Ghost Council using Spike Feeder's second ability by removing a +1/+1 counter from it, causing you to gain 2 life.
Karlov of the Ghost Council triggers, putting two +1/+1 counters on it.
Repeat.

Agatha's Soul Cauldron

Spike Feeder

Give Shalai and Hallar lifelink, if needed.
Gain life.
Karlov of the Ghost Council triggers, putting a +1/+1 counter on it.
Shalai and Hallar triggers, dealing damage to an opponent and causing you to gain life.
Repeat from step 3.

Infinite damage

Card That Gives Lifelink

Shalai and Hallar

Gain life.
Karlov of the Ghost Council triggers, putting two +1/+1 counters on it
All Will Be One triggers, dealing 1 damage to an opponent.
Exquisite Blood triggers, causing you to gain 1 life.
Repeat from step 2.

Infinite lifeloss

All Will Be One

Exquisite Blood

Combos with "Karlov of the Ghost Council"