When Leonin Relic-Warder enters, its first ability triggers, exiling Rescue Skiff.
Activate Shilgengar by sacrificing Leonin Relic-Warder.
When Leonin Relic-Warder dies, its second ability triggers, returning Rescue Skiff from exile to the battlefield.
When Rescue Skiff enters, it triggers, returning Leonin Relic-Warder from your graveyard to the battlefield.
When Leonin Relic-Warder enters, its first ability triggers, exiling Rescue Skiff.
Resolve the Shilgengar ability from step 3.
Repeat from step 3.
This intricate loop transforms a simple pair of peripatetic permanents into a boundless engine of sacrifice and resurrection. By utilizing the enter-the-battlefield trigger of Leonin Relic-Warder to continuously exile Rescue Skiff, you set up a recursive pivot where each death of the cat allows the Skiff to return it straight back to the battlefield. Meanwhile, Shilgengar, Sire of Famine presides over the cycle, happily turning your endlessly looping Leonin Relic-Warder into an inexhaustible harvest of Blood tokens.