Activate Ashnod's Altar by sacrificing Twisted Sewer-Witch, adding {C}{C}.
When Twisted Sewer-Witch dies, Nim Deathmantle triggers, causing you to pay {4} to return Twisted Sewer-Witch from your graveyard to the battlefield, and attach Nim Deathmantle to it.
When Twisted Sewer-Witch enters the battlefield, it triggers, creating a 1/1 Rat creature token, and then creating a Wicked Role Aura token attached to each Rat you control.
Activate Ashnod's Altar by sacrificing the Rat, adding {C}{C}.
The Wicked Role token triggers, causing each opponent to lose 1 life.
Repeat.

Infinite death triggers

Infinite ETB

Infinite lifeloss

Infinite LTB

Infinite sacrifice triggers

Nim Deathmantle

Ashnod's Altar

Twisted Sewer-Witch

Activate Twisted Sewer-Witch by paying {2}, blinking it.
When Twisted Sewer-Witch enters the battlefield, it and Deadeye Navigator's soulbond ability trigger.
Resolve the Deadeye Navigator trigger, repairing it and Twisted Sewer-Witch.
Resolve the Twisted Sewer-Witch trigger, creating a 1/1 Rat creature token, and then creating a Wicked Role Aura token attached to each Rat you control.
Activate Ashnod's Altar by sacrificing the Rat, adding {2}.
The Wicked Role token triggers, causing each opponent to lose 1 life.

Infinite blinking

Deadeye Navigator

Chromatic Orrery

Mycosynth Lattice

Activate Twisted Sewer-Witch by paying {2}, blinking it.
When Twisted Sewer-Witch enters the battlefield, it and Deadeye Navigator's soulbond ability trigger.
Resolve the Deadeye Navigator trigger, repairing it and Twisted Sewer-Witch.
Resolve the Twisted Sewer-Witch trigger, creating a 1/1 Rat creature token, and then creating a Wicked Role Aura token attached to each Rat you control.
Activate Krark-Clan Ironworks by sacrificing the Wicked Role token, adding {2}.
The Wicked Role token triggers, causing each opponent to lose 1 life.

Infinite colorless mana

Infinite creature tokens

Infinite colored mana

Krark-Clan Ironworks

Combos with "Twisted Sewer-Witch"