Attempt to deal any amount of damage to Phyrexian Vindicator.
Phyrexian Vindicator prevents the damage and triggers, dealing that much damage to any target.
Guilty Conscience triggers, attempting to deal that much damage to Phyrexian Vindicator.
Repeat from step 2.

Infinite damage

Guilty Conscience

Phyrexian Vindicator

Cause Stuffy Doll to take damage by any method.
Stuffy Doll triggers, dealing damage to an opponent.
Guilty Conscience triggers, dealing damage to Stuffy Doll.
Repeat from step 2.

Infinite damage to one opponent

Card that gives indestructible

Stuffy Doll

Activate Cacophodon by tapping it, dealing damage to any target.
Guilty Conscience triggers, dealing damage to Cacophodon.
Cacophodon triggers, untapping itself.
Repeat.

Cacophodon

Fire Whip

Deal noncombat damage to Smaug.
Smaug and Wrathful Red Dragon trigger.
Resolve the Smaug trigger, creating at least one Treasure token.
Resolve the Wrathful Red Dragon trigger, causing Smaug to deal damage to any non-Dragon target.
Guilty Conscience triggers, dealing damage to Smaug.
Repeat from step 2.

Infinite Treasure tokens

Infinite artifact ETB

Infinite artifact LTB

Infinite artifact sacrifice triggers

Infinite artifact tokens

Infinite colored mana

Smaug the Impenetrable

Wrathful Red Dragon

Combos with "Guilty Conscience"