Activate Thermopod's second ability by sacrificing Unlucky Witness, adding {R}.
Unlucky Witness dies, triggering itself and Mortuary.
Resolve the Mortuary trigger, putting Unlucky Witness on top of your library.
Resolve the Unlucky Witness trigger, exiling the top two cards of your library.
Cast Unlucky Witness from exile by paying {R}.
Repeat.

Exile your library

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Unlucky Witness

Mortuary

Thermopod

Activate Phyrexian Altar by sacrificing Unlucky Witness, adding {R}.
Unlucky Witness dies, triggering itself and Mortuary.
Resolve the Mortuary trigger, putting Unlucky Witness on top of your library.
Resolve the Unlucky Witness trigger, exiling the top two cards of your library.
Cast Unlucky Witness from exile by paying {R}.
Repeat.

Combos with "Unlucky Witness"