Agatha's Soul Cauldron, Inquisitive Puppet, and Sigil Captain

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Inquisitive Puppet in exile
• Sigil Captain on the battlefield
• You control another creature that has at least one +1/+1 counter on it

Steps

1. Activate another creature you control that has a +1/+1 counter on it by exiling it, creating a 1/1 Human creature token
2. When the Human enters the battlefield, Sigil Captain triggers, putting two +1/+1 counters on it
3. Repeat using the Human token instead

Results

• Infinite ETB
• Infinite LTB