Diamond Lion, First Day of Class, Dross Scorpion, and Cauldron of Souls

Prerequisites

• Diamond Lion on the battlefield
• First Day of Class in hand
• Dross Scorpion on the battlefield
• Cauldron of Souls on the battlefield
• Diamond Lion does not have summoning sickness

Steps

1. Activate Cauldron of Souls, giving Diamond Lion persist until end of turn
2. Activate Diamond Lion by tapping it, discarding your hand, and sacrificing it, adding three mana of any one color
3. Diamond Lion's persist ability and Dross Scorpion both trigger
4. Resolve the Dross Scorpion ability, untapping Cauldron of Souls
5. Resolve the Diamond Lion's persist ability, returning it from the graveyard to the battlefield with a -1/-1 counter on it
6. First Day of Class triggers, putting a +1/+1 counter on Diamond Lion and giving Diamond Lion haste until end of turn
7. Repeat

Results

• Infinite colored mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers