Yenna, Redtooth Regent, Agatha's Soul Cauldron, Ashnod's Altar, and Breaching Hippocamp

Prerequisites

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

Steps

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

Results

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