Cast Channel by paying {G}{G}.
Activate Phyrexian Altar by sacrificing Hollowhenge Scavenger, adding {U}.
When Hollowhenge Scavenger dies, Fool's Demise's first and second abilities trigger.
Resolve the first Fool's Demise trigger, returning Hollowhenge Scavenger from your graveyard to the battlefield.
When Hollowhenge Scavenger enters the battlefield, it triggers, causing you to gain 5 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 Hollowhenge Scavenger.
Repeat from step 2.

Infinite colorless mana

Infinite death triggers

Infinite ETB

Infinite lifegain

Infinite lifegain triggers

Infinite LTB

Infinite sacrifice triggers

Infinite storm count

Fool's Demise

Channel

Phyrexian Altar

Hollowhenge Scavenger

Combos with "Hollowhenge Scavenger"