Venser, Corpse Puppet, Tainted Observer, and Ashnod's Altar

Prerequisites

• Venser, Corpse Puppet on the battlefield
• Tainted Observer on the battlefield
• Ashnod's Altar on the battlefield
• You have a way to cause a creature to enter the battlefield under your control
• available

Steps

1. Cause a creature to enter the battlefield under your control
2. Tainted Observer triggers, causing you to pay to proliferate
3. Venser triggers, creating a legendary 3/3 The Hollow Sentinel artifact creature token
4. The Hollow Sentinel enters the battlefield, triggering Tainted Observer
5. Holding priority, activate Ashnod's Altar by sacrifcing The Hollow Sentinel, adding
6. Resolve the Tainted Observer trigger, causing you to pay to proliferate
7. Repeat from step 3

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite proliferate
• Infinite sacrifice triggers