Othelm, Sigardian Outcast, Ashnod's Altar, and Great Oak Guardian

Prerequisites

• Othelm, Sigardian Outcast on the battlefield
• Ashnod's Altar on the battlefield
• Great Oak Guardian on the battlefield
• Othelm does not have summoning sickness

Steps

1. Activate Ashnod's Altar by sacrificing Great Oak Guardian, adding
2. Activate Othelm by paying and tapping it, returning Great Oak Guardian from your graveyard to the battlefield
3. Great Oak Guardian enters the battlefield, untapping all creatures you control and giving them +2/+2 until end of turn
4. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinitely large creatures until end of turn
• Infinite sacrifice triggers
• Infinite tap triggers
• Infinite untap of all creatures you control
• Infinitely large creatures you control until end of turn
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce