Activate Viscera Seer by sacrificing the persist creature.
When the persist creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Thran Vigil triggers, putting a +1/+1 counter on the persist creature.
Resolve the Viscera Seer ability, causing you to scry 1.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Infinite scry 1

Persist Creature

Thran Vigil

Viscera Seer

Activate the Goblin sacrifice outlet by sacrificing Putrid Goblin.
When Putrid Goblin dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Thran Vigil triggers, putting a +1/+1 counter on Putrid Goblin.
Resolve the Goblin sacrifice outlet ability.
Repeat.
This combo will provide infinite results of whatever the Goblin sacrifice outlet produces, which will vary depending on the sacrifice outlet used.

Creature with "Sacrifice a Goblin:"

Putrid Goblin

Activate Serrated Biskelion by tapping it, putting a -1/-1 counter on it and Butcher Ghoul.
Activate Phyrexian Altar by sacrificing Butcher Ghoul, adding one mana of any color.
When Butcher Ghoul dies, its undying ability and Serrated Biskelion trigger.
Resolve the Serrated Biskelion trigger, untapping it.
Resolve the Butcher Ghoul trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Butcher Ghoul leaves your graveyard, Thran Vigil triggers, putting a +1/+1 counter on Serrated Biskelion.
Repeat.

Infinite colored mana

Infinite lifeloss

Serrated Biskelion

Thornbite Staff

Phyrexian Altar

Butcher Ghoul

Activate Serrated Biskelion by tapping it, putting a -1/-1 counter on it and Geralf's Messenger.
Activate Ashnod's Altar by sacrificing Geralf's Messenger, adding {C}{C}.
When Geralf's Messenger dies, its undying ability and Serrated Biskelion trigger.
Resolve the Serrated Biskelion trigger, untapping it.
Resolve the Geralf's Messenger trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Geralf's Messenger enters the battlefield, it and Thran Vigil trigger.
Resolve the Geralf's Messenger trigger, causing an opponent to lose 2 life.
Resolve the Thran Vigil trigger, putting a +1/+1 counter on Serrated Biskelion.
Repeat.

Infinite colorless mana

Ashnod's Altar

Geralf's Messenger

Activate Serrated Biskelion by tapping it, putting a -1/-1 counter on it and Geralf's Messenger.
Activate Phyrexian Altar by sacrificing Geralf's Messenger, adding one mana of any color.
When Geralf's Messenger dies, its undying ability and Serrated Biskelion trigger.
Resolve the Serrated Biskelion trigger, untapping it.
Resolve the Geralf's Messenger trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Geralf's Messenger enters the battlefield, it and Thran Vigil trigger.
Resolve the Geralf's Messenger trigger, causing an opponent to lose 2 life.
Resolve the Thran Vigil trigger, putting a +1/+1 counter on Serrated Biskelion.
Repeat.

Activate Serrated Biskelion by tapping it, putting a -1/-1 counter on it and Butcher Ghoul.
Activate Ashnod's Altar by sacrificing Butcher Ghoul, adding {C}{C}.
When Butcher Ghoul dies, its undying ability and Serrated Biskelion trigger.
Resolve the Serrated Biskelion trigger, untapping it.
Resolve the Butcher Ghoul trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Butcher Ghoul leaves your graveyard, Thran Vigil triggers, putting a +1/+1 counter on Serrated Biskelion.
Repeat.

Activate Serrated Biskelion by tapping it, putting a -1/-1 counter on it and Evernight Shade.
Activate Phyrexian Altar by sacrificing Evernight Shade, adding one mana of any color.
When Evernight Shade dies, its undying ability and Serrated Biskelion trigger.
Resolve the Serrated Biskelion trigger, untapping it.
Resolve the Evernight Shade trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Evernight Shade leaves your graveyard, Thran Vigil triggers, putting a +1/+1 counter on Serrated Biskelion.
Repeat.

Evernight Shade

Activate Serrated Biskelion by tapping it, putting a -1/-1 counter on it and Evernight Shade.
Activate Ashnod's Altar by sacrificing Evernight Shade, adding {C}{C}.
When Evernight Shade dies, its undying ability and Serrated Biskelion trigger.
Resolve the Serrated Biskelion trigger, untapping it.
Resolve the Evernight Shade trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Evernight Shade leaves your graveyard, Thran Vigil triggers, putting a +1/+1 counter on Serrated Biskelion.
Repeat.

Combos with "Thran Vigil"