Deal damage to Overgrown Armasaur.
Overgrown Armasaur and Blazing Sunsteel trigger.
Resolve the Overgrown Armasaur trigger, creating a creature token.
Resolve the Blazing Sunsteel trigger, dealing damage to Overgrown Armasaur.
Repeat from step 2.

Infinite damage

Infinite creature ETB

Infinite creature tokens

Blazing Sunsteel

Overgrown Armasaur

Give Overgrown Armasaur indestructible by any method.
Deal damage to Overgrown Armasaur.
Overgrown Armasaur triggers, creating a 1/1 Saproling creature token.
The Saproling enters the battlefield, triggering Warstorm Surge, causing the Saproling to deal one damage to Overgrown Armasaur.
Repeat from step 3.

Warstorm Surge

Give Overgrown Armasaur indestructible by any method.
Deal damage to Overgrown Armasaur.
Overgrown Armasaur triggers, creating a 1/1 Saproling creature token.
The Saproling enters the battlefield, triggering Terror of the Peaks, dealing 1 damage to Overgrown Armasaur.
Repeat from step 3.

Terror of the Peaks

Give Overgrown Armasaur indestructible, if needed.
Cause a creature to enter the battlefield under your control.
Halana triggers, causing you to pay {2} to have that creature deal damage equal to its power to Overgrown Armasaur.
Overgrown Armasaur triggers, causing you to create a 1/1 Saproling creature token.
When the Saproling enters the battlefield, Halana triggers.
Holding priority, activate Ashnod's Altar by sacrificing the Saproling, adding {C}{C}.
Resolve the Halana trigger, causing you to pay {2} to deal 1 damage to Overgrown Armasaur.
Repeat from step 4.

Infinite death triggers

Infinite creature LTB

Infinite creature sacrifice triggers

Halana, Kessig Ranger

Ashnod's Altar

Activate Ashnod's Altar by sacrificing Thorin, adding {C}{C}.
When Thorin dies, Nim Deathmantle triggers, causing you to pay {4} to return Thorin from your graveyard to the battlefield and attach Nim Deathmantle to it.
When Thorin enters, it triggers, attaching Nim Deathmantle to Overgrown Armasaur, and then having it deal damage to itself.
Overgrown Armasaur triggers, creating a creature token.
Activate Ashnod's Altar by sacrificing the creature token, adding {C}{C}.
Repeat.

Combos with "Overgrown Armasaur"