Activate Phyrexian Altar by sacrificing Gutterbones, adding {B}.
Activate Gutterbones by paying {B}, returning it to your hand.
Desecrated Tomb trigger, creating a 1/1 Bat token.
Activate Phyrexian Altar by sacrificing a Bat token, adding {B}.
Cast Gutterbones by paying {B}.
Repeat

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Embalmer's Tools

Phyrexian Altar

Desecrated Tomb

Gutterbones

Activate Phyrexian Altar by sacrificing Gutterbones, adding {B}.
Activate Gutterbones by paying {B}, returning it to your hand.
Tormod trigger, creating a 2/2 Zombie token.
Activate Phyrexian Altar by sacrificing a Zombie token, adding {B}.
Cast Gutterbones by paying {B}.
Repeat

Infinite death triggers

Tormod, the Desecrator

Cast Gutterbones by paying {B}.
Reflections of Littjara triggers, creating a token copy of Gutterbones.
Activate Ashnod's Altar by sacrificing Gutterbones and the Gutterbones token, adding {C}{C}{C}{C}.
The Gutterboness die, triggering Pitiless Plunderer twice, creating two Treasure tokens.
Activate both Treasure tokens by tapping and sacrificing them, adding {B}{B}.
Activate Gutterbones by paying {1}{B}, returning it from your graveyard to your hand.
Repeat.

Infinite colorless mana

Infinite storm count

Reflections of Littjara

Pitiless Plunderer

Ashnod's Altar

Cast Gutterbones by paying {B}.
Reflections of Littjara triggers, creating a token copy of Gutterbones.
Activate Phyrexian Altar by sacrificing Gutterbones and the Gutterbones token, adding {2}.
The Gutterboness die, triggering Pitiless Plunderer twice, creating two Treasure tokens.
Activate both Treasure tokens by tapping and sacrificing them, adding {B}{B}.
Activate Gutterbones by paying {1}{B}, returning it from your graveyard to your hand.
Repeat.

Infinite creature tokens

Infinite colored mana

Infinite Treasure tokens

Combos with "Gutterbones"