An opponent controls a creature with toughness six or less.
You do not control an Army.
({11} magic symbol) ({R} magic symbol) available.
Steps
Activate That Which Was Taken by paying ({4} magic symbol) and tapping it, putting a divinity counter on a creature an opponent controls with toughness six or less.
Activate Fall of Cair Andros by paying ({7} magic symbol) ({R} magic symbol) , dealing seven damage to the creature that has a divinity counter on it.
Fall of Cair Andros triggers, creating a 0/0 Army and putting at least one +1/+1 counter on it.
When the Army enters the battlefield, Terror of the Peaks triggers.
Holding priority, Activate Thermopod's second ability by sacrificing the Army, adding ({R} magic symbol) .
Resolve the Terror of the Peaks trigger, dealing 1 damage to the creature with a divinity counter on it.
Repeat from step 3.
Once you have infinite red mana, with a Terror of the Peaks trigger on the stack, you may use Fall of Cair Andros' ability to deal infinite damage to the creature with a divinity counter on it, thus causing the Army to have infinite +1/+1 counters on it, which causes Terror of the Peaks to deal infinite damage to any target.