Activate Ashnod's Altar by sacrificing Brindle Shoat, adding {C}{C}.
When Brindle Shoat dies, it and Nim Deathmantle triggers.
Resolve the Brindle Shoat trigger, creating a 3/3 Boar creature token.
Activate Ashnod's Altar by sacrificing the Boar, adding {C}{C}.
Resolve the Nim Deathmantle trigger from step 2, causing you to pay {4} to return Brindle Shoat from your graveyard to the battlefield, and attach Nim Deathmantle to it.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Nim Deathmantle

Ashnod's Altar

Brindle Shoat

Sacrifice Brindle Shoat to activate Phyrexian Altar, adding {G}.
Brindle Shoat's death trigger creates a 3/3 Boar token.
Sacrifice the Boar to activate Phyrexian Altar, adding {G}.
Return Brindle Shoat to your hand using Colfenor's trigger.
Repeat.

Combos with "Brindle Shoat"