Boonweaver Giant, Fool's Demise, and Ashnod's Altar

Prerequisites

• Boonweaver Giant on the battlefield
• Fool's Demise on the battlefield
• Ashnod's Altar on the battlefield
• Fool's Demise attached to Boonweaver Giant

Steps

1. Activate Ashnod's Altar by sacrificing Boonweaver Giant, adding
2. Boonweaver Giant dies, triggering Fool's Demise's first and second abilities
3. Resolve Fool's Demise's first trigger, returning Boonweaver Giant to the battlefield
4. Boonweaver Giant enters the battlefield, returning Fool's Demise from your graveyard to the battlefield attached to Boonweaver Giant
5. Fool's Demise's second trigger from step 2 fails to resolve due to having no legal target
6. Repeat

Results

• Infinite colorless mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers