Cast Squee from your graveyard or from exile by paying {1}{R}{R}.
Iraxxa and Birgi trigger.
Resolve the Iraxxa trigger, creating a 2/2 Alien Warrior creature token.
Resolve the Birgi trigger, adding {R}.
Activate Phyrexian Altar twice by sacrificing Squee and the Alien Warrior, adding {R}{R}.
Repeat.

Infinite LTB

Infinite ETB

Infinite sacrifice triggers

Infinite death triggers

Infinite storm count

Iraxxa, Empress of Mars

Squee, the Immortal

Phyrexian Altar

Birgi, God of Storytelling // Harnfel, Horn of Bounty

If Runaway Steam-Kin has tree or more +1/+1 counters on it, activate it by removing three +1/+1 counters from it, adding {R}{R}{R}.
Cast Squee from your graveyard or from exile by paying {1}{R}{R}.
Iraxxa and Runaway Steam-Kin trigger.
Resolve the Iraxxa trigger, creating a 2/2 Alien Warrior creature token.
Resolve the Runaway Steam-Kin trigger, putting a +1/+1 counter on it.
Activate Thermopod's second ability twice by sacrificing Squee and the Alien Warrior, adding {R}{R}.
Repeat.

Thermopod

Runaway Steam-Kin

Activate Ashnod's Altar by sacrificing Eternal Scourge, adding {C}{C}.
Eternal Scourge is exiled instead of being put into your graveyard due to Rest in Peace.
Cast Eternal Scourge from exile by paying {3}.
Iraxxa triggers, creating a 2/2 Alien Warrior creature token.
Activate Ashnod's Altar twice by sacrificing the Alien Warrior and Eternal Scourge, adding {C}{C}{C}{C}.
Repeat from step 2.

Infinite colorless mana

Infinite creature tokens

Eternal Scourge

Ashnod's Altar

Rest in Peace

Cast Squee from your graveyard or from exile by paying {1}{R}{R}.
Iraxxa triggers, creating two 2/2 Alien Warrior creature tokens.
Activate Phyrexian Altar three times by sacrificing Squee and the Alien Warriors, adding {1}{R}{R}.
Repeat.

Parallel Lives

Cast Squee from your graveyard or from exile by paying {1}{R}{R}.
Iraxxa triggers, creating a 1/1 Frog and a 2/2 Alien Warrior creature token.
Activate Thermopod three times by sacrificing Squee, the Frog and the Alien Warrior, adding {R}{R}{R}.
Repeat.

Combos with "Iraxxa, Empress of Mars"