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

Declare any creature as an attacker. Dawnsire triggers, attempting to deal 100 damage to Phyrexian Vindicator.
The damage to Phyrexian Vindicator is prevented, triggering Phyrexian Vindicator, dealing 100 damage to any target.

Near-infinite damage to one opponent

Dawnsire, Sunstar Dreadnought

Cast Martyrdom by paying {1}{W}{W}, targeting Phyrexian Vindicator.
Activate Phyrexian Vindicator by paying {0}, targeting a creature.
Attempt to deal damage to the targeted creature. The damage will then be increased due to Dictate of the Twin Gods, then redirected to Phyrexian Vindicator, which is then redirected back to the creature that was originally targeted.
Holding priority, activate Phyrexian Vindicator by paying {0}, targeting the creature. 
Repeat step 4 until all damage will be redirected to Phyrexian Vindicator.
Repeat from step 3.

Infinite damage to one opponent

Martyrdom

Dictate of the Twin Gods

Declare Phyrexian Vindicator as an attacker.
Holding priority, activate Catapult Squad by tapping two Soldiers, attempting to deal 2 damage to Phyrexian Vindicator.
The damage is prevented due to Phyrexian Vindicator's replacement effect. Phyrexian Vindicator triggers, dealing 2 damage to you.
Darien triggers, creating two 1/1 Soldier creature tokens.
When the Soldiers enter the battlefield, Soul Warden triggers twice, causing you to gain 2 life.
Repeat from step 2.

Combos with "Phyrexian Vindicator"