Activate Xavier Sal by tapping it and removing a counter from a permanent you control, creating a copy of a creature token you control.
When the creature token enters the battlefield, Intruder Alarm and Cloakwood Swarmkeeper trigger.
Resolve the Intruder Alarm trigger, untapping all creatures.
Resolve the Cloakwood Swarmkeeper trigger, putting a counter on it.
Repeat.

Infinite creature tokens

Infinite ETB

Infinite mana creatures you control can produce

Infinite copies of creature tokens you control

Infinite untap of all creatures

Xavier Sal, Infested Captain

Intruder Alarm

Cloakwood Swarmkeeper

Cause a token to enter the battlefield under your control.
The token enters the battlefield, triggering Cloakwood Swarmkeeper, putting a +1/+1 counter on Cloakwood Swarmkeeper.
Animation Module triggers.
Holding priority, activate Ashnod's Altar by sacrificing the token, adding {C}{C}.
Resolve the Animation Module trigger, causing you to pay {1} to create a 1/1 Servo artifact creature token.
Repeat from step 2.

Infinite +1/+1 counters on Cloakwood Swarmkeeper

Infinite colorless mana

Infinite death triggers

Infinite LTB

Infinite sacrifice triggers

Animation Module

Ashnod's Altar

Cause a token to enter the battlefield under your control.
The token enters the battlefield, triggering Cloakwood Swarmkeeper, putting a +1/+1 counter on Cloakwood Swarmkeeper.
Animation Module triggers.
Holding priority, activate Phyrexian Altar by sacrificing the token, adding {1}.
Resolve the Animation Module trigger, causing you to pay {1} to create a 1/1 Servo artifact creature token.
Repeat from step 2.

Phyrexian Altar

Cause a token to enter the battlefield under your control.
The token enters the battlefield, triggering Cloakwood Swarmkeeper, putting a +1/+1 counter on Cloakwood Swarmkeeper.
Animation Module triggers.
Holding priority, activate Krark-Clan Ironworks by sacrificing the token, adding {C}{C}.
Resolve the Animation Module trigger, causing you to pay {1} to create a 1/1 Servo artifact creature token.
Repeat from step 2.

Krark-Clan Ironworks

Put a +1/+1 counter on a creature you control.
Moss-Pit Skeleton triggers, putting it from your graveyard onto the top of your library.
Chalk Outline triggers, creating a 2/2 Detective creature token and a Clue token.
When the Clue enters the battlefield, Sarinth Steelseeker and Cloakwood Swarmkeeper trigger.
Resolve the Sarinth Steelseeker trigger, putting Moss-Pit Skeleton from the top of your library into your graveyard.
Resolve the Cloakwood Swarmkeeper trigger, putting a +1/+1 counter on it.
Repeat from step 2.

Infinite Clue tokens

Infinite +1/+1 counters on a creature

Chalk Outline

Sarinth Steelseeker

Moss-Pit Skeleton

Put a +1/+1 counter on a creature you control.
Moss-Pit Skeleton triggers, putting it from your graveyard onto the top of your library.
Kheru Goldkeeper triggers, creating a Treasure token.
When the Treasure enters the battlefield, Transplant Theorist and Cloakwood Swarmkeeper trigger.
Resolve the Transplant Theorist trigger, drawing Moss-Pit Skeleton from your library, and then discarding it.
Resolve the Cloakwood Swarmkeeper trigger, putting a +1/+1 counter on it.
Repeat from step 2.

Infinite colored mana

Infinite self-discard triggers

Infinite draw triggers

Infinite Treasure tokens

Kheru Goldkeeper

Transplant Theorist

Put a +1/+1 counter on a creature you control.
Moss-Pit Skeleton triggers, putting it from your graveyard onto the top of your library.
Chalk Outline triggers, creating a 2/2 Detective creature token and a Clue token.
When the Clue and Detective enter the battlefield, Sage of the Falls and Cloakwood Swarmkeeper trigger.
Resolve the Sage of the Falls trigger, drawing Moss-Pit Skeleton from your library, and then discarding it.
Resolve the Cloakwood Swarmkeeper trigger, putting a +1/+1 counter on it.
Repeat from step 2.

Near-infinite ETB

Infinite looting

Near-infinite creature tokens

Near-infinite +1/+1 counters on a creature

Near-infinite Clue tokens

Sage of the Falls

Put a +1/+1 counter on a creature you control.
Moss-Pit Skeleton triggers, putting it from your graveyard onto the top of your library.
Chalk Outline triggers, creating a 2/2 Detective creature token and a Clue token.
When the Clue enters the battlefield, Golbez and Cloakwood Swarmkeeper trigger.
Resolve the Golbez trigger, putting Moss-Pit Skeleton from the top of your library into your graveyard.
Resolve the Cloakwood Swarmkeeper trigger, putting a +1/+1 counter on it.
Repeat from step 2.

Golbez, Crystal Collector

Put a +1/+1 counter on a creature you control.
Moss-Pit Skeleton triggers, putting it from your graveyard onto the top of your library.
Kheru Goldkeeper triggers, creating a Treasure token
When the Treasure enters the battlefield, Golbez and Cloakwood Swarmkeeper trigger.
Resolve the Golbez trigger, putting Moss-Pit Skeleton from the top of your library into your graveyard.
Resolve the Cloakwood Swarmkeeper trigger, putting a +1/+1 counter on it.
Repeat from step 2.

Put a +1/+1 counter on a creature you control.
Moss-Pit Skeleton triggers, putting it from your graveyard onto the top of your library.
Kheru Goldkeeper triggers, creating a Treasure token
When the Treasure enters the battlefield, Sarinth Steelseeker and Cloakwood Swarmkeeper trigger.
Resolve the Sarinth Steelseeker trigger, putting Moss-Pit Skeleton from the top of your library into your graveyard.
Resolve the Cloakwood Swarmkeeper trigger, putting a +1/+1 counter on it.
Repeat from step 2.

Combos with "Cloakwood Swarmkeeper"