Voracious Brood dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to its replacement effect.
Resolve the
Shilgengar ability.
Repeat.
Results
Infinite Blood tokens.
Infinite ETB.
Infinite LTB.
Infinite death triggers.
Infinite sacrifice triggers.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).