Activate Ashnod's Altar by sacrificing Rendmaw, adding {C}{C}.
When Rendmaw dies, Nim Deathmantle triggers, causing you to pay {4} to return Rendmaw from your graveyard to the battlefield, and attach Nim Deathmantle to it.
When Rendmaw enters the battlefield, it triggers, causing each player to create a tapped 2/2 Bird creature token.
Activate Ashnod's Altar by sacrificing the Bird, adding {C}{C}.
Repeat.

Infinite creature LTB

Infinite creature ETB

Infinite creature sacrifice triggers

Infinite death triggers

Infinite creature ETB for opponents

Infinite tapped creature tokens for opponents

Rendmaw, Creaking Nest

Nim Deathmantle

Ashnod's Altar

Cast the creature with mana value 0 from your hand by paying {0}.
Rendmaw triggers, causing each player to create a tapped 2/2 Bird creature token.
When the Bird enters the battlefield under your control, Cloudstone Curio triggers, returning a nontoken creature with mana value 0 from the battlefield to your hand.
Resolve the creature spell cast in step 1.
Repeat.

Infinite storm count

Infinite creature ETB for all players

Infinite tapped creature tokens for all players

Cloudstone Curio

Memnite

Ornithopter

Cast Perilous Myr by paying {2}.
Rendmaw triggers, causing each player to create a tapped 2/2 Bird creature token with flying and that is goaded for the rest of the game.
Activate Ashnod's Altar by sacrificing Perilous Myr, adding {C}{C}.
When Perilous Myr dies, it triggers, dealing 2 damage to a Bird token an opponent controls, thus killing the Bird.
Glissa triggers, returning Perilous Myr from your graveyard to your hand.
Repeat.

Combos with "Rendmaw, Creaking Nest"