Activate Shilgengar by sacrificing Trapjaw Kelpie.
When Trapjaw Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to Vizier of Remedies.
Resolve the Shilgengar ability
Repeat.
This engine operates as a perpetual sacrificial loop by pairing Trapjaw Kelpie with the bone-shriving greed of Shilgengar, Sire of Famine. Because Trapjaw Kelpie features persist, it would normally return with a -1/-1 counter and extinguish itself after a single recursion, but Vizier of Remedies intervenes to completely nullify that counter placement. This allows Shilgengar, Sire of Famine to continuously sacrifice the same beast to fuel an endless cascade of Blood tokens and death triggers without ever running out of fodder.