Yenna, Redtooth Regent, Ashnod's Altar, Jump Scare, and Great Oak Guardian

Prerequisites

• Yenna, Redtooth Regent on the battlefield
• Ashnod's Altar on the battlefield
• Jump Scare in hand
• Great Oak Guardian on the battlefield
• available

Steps

1. Cast Jump Scare by paying , targeting Great Oak Guardian
2. Activate Yenna by paying and tapping it, creating a token copy of Great Oak Guardian
3. When the Great Oak Guardian token enters, it triggers, untapping all creatures you control and giving them +2/+2 until end of turn
4. Activate Ashnod's Altar by sacrificing the Great Oak Guardian token, adding
5. Repeat from step 2

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinite power and toughness for creatures you control until end of turn