When Karmic Guide dies, Body Launderer's first ability triggers, causing Body Launderer to connive.
Resolve the Shilgengar ability.
Activate Shilgengar by sacrificing Body Launderer.
When Body Launderer dies, its second ability triggers, returning Karmic Guide from your graveyard to the battlefield.
When Karmic Guide enters, it triggers, returning Body Launderer from your graveyard to the battlefield.
Resolve the Shilgengar ability.
Repeat.
This elegant loop operates as a self-sustaining cycle of sacrifice and resurrection, anchored by Shilgengar, Sire of Famine and his ability to turn fallen allies into Blood tokens. By repeatedly feeding Karmic Guide and Body Launderer to Shilgengar, you trigger Karmic Guide's entry ability to pull Body Launderer back from the graveyard, while Body Launderer's death trigger naturally resurrects Karmic Guide in return. Meanwhile, Body Launderer's connive trigger lets you cycle through your deck and discard extra cards, further fueling the engine and keeping your graveyard well-stocked.