Cast Channel by paying {G}{G}.
Activate Phyrexian Altar by sacrificing Spiritual Guardian, adding {U}.
When Spiritual Guardian dies, Fool's Demise's first and second abilities trigger.
Resolve the first Fool's Demise trigger, returning Spiritual Guardian from your graveyard to the battlefield.
When Spiritual Guardian enters the battlefield, it triggers, causing you to gain 4 life.
Resolve the second Fool's Demise trigger, returning it from your graveyard to your hand.
Activate Channel four times by paying 4 life, adding {C}{C}{C}{C}.
Cast Fool's Demise by paying {4}{U}, attaching it to Spiritual Guardian.
Repeat from step 2.

Infinite death triggers

Infinite ETB

Infinite lifegain triggers

Infinite LTB

Infinite sacrifice triggers

Infinite storm count

Fool's Demise

Channel

Phyrexian Altar

Spiritual Guardian

Combos with "Spiritual Guardian"