Agatha's Soul Cauldron, Lurking Roper, and Temple Elder

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Lurking Roper on the battlefield
• Temple Elder in exile
• Lurking Roper has at least one +1/+1 counter on it and does not have summoning sickness
• It is your precombat main phase

Steps

1. During your precombat main phase, activate Lurking Roper using Temple Elder's ability by tapping it, causing you to gain 1 life
2. Lurking Roper triggers, untapping itself
3. Repeat

Results

• Infinite lifegain
• Infinite lifegain triggers