Activate Ashnod's Altar by sacrificing Scampering Scorcher, adding {C}{C}.
Scampering Scorcher dies, triggering Nim Deathmantle, causing you to pay {4} to return Scampering Scorcher from your graveyard to the battlefield, and attach Nim Deathmantle to it.
Scampering Scorcher enters the battlefield, creating two 1/1 Elemental creature tokens and giving Elementals you control haste until end of turn.
Activate Ashnod's Altar by sacrificing an Elemental token, adding {C}{C}.
Repeat.

Infinite colorless mana

Infinite creature tokens with haste

Infinite death triggers

Infinite creature ETB

Infinite creature LTB

Infinite creature sacrifice triggers

Nim Deathmantle

Ashnod's Altar

Scampering Scorcher

Activate Horde of Notions by paying {5}, casting Scampering Scorcher from your graveyard without paying its mana cost.
When Scampering Scorcher enters the battlefield, it triggers, creating two 1/1 Elemental creature tokens and giving Elementals you control haste until end of turn.
Activate Ashnod's Altar three times by sacrificing Scampering Scorcher and two Elementals, adding six {C}.
Repeat.

Combos with "Scampering Scorcher"