Wight of the Reliquary does not have summoning sickness.
Thornbite Staff attached to Wight of the Reliquary.
You control at least one additional creature.
Steps
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, each Scute Swarm you control triggers, creating that many 1/1 Insect creature tokens or that many token copies of Scute Swarm.
Repeat.
Results
Near-infinite landfall triggers.
Put all land cards from your library onto the battlefield tapped.