Cast any nonartifact creature with mana value three or less from your hand by paying {0} due to Aluren.
When the creature enters the battlefield, Cloudstone Curio triggers, returning another nontoken nonartifact creature with mana value three or less.
Repeat.
Cast Ferocious Pup by paying {0} due to Aluren.
When Ferocious Pup enters the battlefield, it and Cloudstone Curio trigger.
Resolve the Cloudstone Curio trigger, returning nothing from the battlefield to your hand.
Resolve the Ferocious Pup trigger, creating a 2/2 Wolf creature token.
When the Wolf enters the battlefield, Cloudstone Curio triggers, returning Ferocious Pup from the battlefield to your hand.
Repeat.

Infinite LTB

Infinite ETB

Infinite storm count

Infinite creature tokens

Aluren

Cloudstone Curio

Ferocious Pup

Activate Ashnod's Altar by sacrificing Ferocious Pup, adding {C}{C}.
When Ferocious Pup dies, Nim Deathmantle triggers, causing you to pay {4} to return Ferocious Pup from your graveyard to the battlefield, and attach Nim Deathmantle to it.
When Ferocious Pup enters the battlefield, it triggers, creating a 2/2 Wolf creature token.
Activate Ashnod's Altar by sacrificing the Wolf, adding {C}{C}.
Repeat.

Infinite death triggers

Infinite sacrifice triggers

Nim Deathmantle

Ashnod's Altar

Combos with "Ferocious Pup"