Yenna, Redtooth Regent, Agatha's Soul Cauldron, Ashnod's Altar, and Hyrax Tower Scout

Prerequisites

• Yenna, Redtooth Regent on the battlefield
• Agatha's Soul Cauldron on the battlefield
• Ashnod's Altar on the battlefield
• Hyrax Tower Scout on the battlefield
• plus enough mana to activate the Licid's ability available

Steps

1. Activate Hyrax Tower Scout using the Licid's ability by paying its activation cost, attaching Hyrax Tower Scout to Yenna and causing Hyrax Tower Scout to become an Aura
2. Activate Yenna by paying and tapping it, creating a token copy of Hyrax Tower Scout
3. When the Hyrax Tower Scout token enters, it triggers, untapping Yenna
4. Activate Ashnod's Altar by sacrificing the Hyrax Tower Scout token, adding
5. Repeat from step 2

Results

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