Activate Wight of the Reliquary by tapping it and sacrificing another creature, causing you to search your library for a land card and put it onto the battlefield tapped.
When the land enters the battlefield, Retreat to Coralhelm and each Scute Swarm you control triggers.
Resolve each Scute Swarm trigger, creating that many 1/1 Insect creature tokens or that many token copies of Scute Swarm.
Resolve the Retreat to Coralhelm trigger, untapping Wight of the Reliquary.
Repeat.

Near-infinite creature ETB

Near-infinite landfall triggers

Near-infinite creature tokens

Put all lands from your library onto the battlefield tapped

Wight of the Reliquary

Scute Swarm

Retreat to Coralhelm

Activate Wight of the Reliquary by tapping it and sacrificing Bloodghast, causing you to search your library for a land card and put it onto the battlefield tapped.
When the land enters the battlefield, Bloodghast and Retreat to Coralhelm trigger.
Resolve the Bloodghast trigger, returning it from your graveyard to the battlefield.
Resolve the Retreat to Coralhelm trigger, untapping Wight of the Reliquary.
Repeat.

Bloodghast

Activate Wight of the Reliquary by tapping it and sacrificing another creature, causing you to search your library for a land card and put it onto the battlefield tapped.
When the land enters the battlefield, each Scute Swarm you control triggers.
Resolve the first trigger, creating either a 1/1 Insect creature token or a token copy of Scute Swarm.
When the creature token enters the battlefield, Intruder Alarm triggers, untapping all creatures.
Repeat from step 3 for each remaining trigger, if applicable.
Repeat from step 1.

Near-infinite untap of all creatures

Intruder Alarm

Activate Wight of the Reliquary by tapping it and sacrificing Bloodghast.
When Bloodghast dies, Wight of the Reliquary triggers, untapping Wight of the Reliquary.
Resolve the Wight of the Reliquary ability from step 1, causing you to search your library for a land card and put it onto the battlefield tapped.
When the land enters the battlefield, Bloodghast triggers, returning itself from your graveyard to the battlefield.
Repeat.

Thornbite Staff

Activate Wight of the Reliquary by tapping it and sacrificing another creature.
When the creature dies, Wight of the Reliquary triggers, untapping Wight of the Reliquary.
Resolve the Wight of the Reliquary ability from step 1, causing you to search your library for a land card and put it onto the battlefield tapped.
When the land enters the battlefield, Scute Swarm triggers, creating a creature token.
Repeat.

Near-infinite creature LTB

Near-infinite creature sacrifice triggers

Near-infinite death triggers

Activate a creature you control that has a +1/+1 counter on it by tapping it and sacrificing Bloodghast, searching your library for a land card and putting it onto the battlefield tapped.
When the land enters, Bloodghast triggers, returning itself from your graveyard to the battlefield tapped.
Insidious Roots triggers, creating a 0/1 Plant creature token and then putting a +1/+1 counter on each Plant you control.
Repeat using the Plant instead until no lands are in your library.

Combos with "Wight of the Reliquary"