Bigger on the Inside + Blossoming Tortoise + Deserted Temple + Rings of Brighthearth

Bigger on the Inside

Blossoming Tortoise

Deserted Temple

Rings of Brighthearth

How it works

1. Activate Deserted Temple's second ability by paying 0 due to Blossoming Tortoise and tapping it, targeting itself.
2. Rings of Brighthearth triggers, causing you to pay 2 to copy Deserted Temple's ability, targeting Deserted Temple.
3. Resolve the copy of Deserted Temple's ability, untapping it.
4. Activate Deserted Temple by tapping it, adding two mana of any color and causing the next spell you cast this turn to have cascade.
5. Resolve the Deserted Temple ability from step 1, untapping it.
6. Repeat.
7. Cast any nonland card from your hand by paying its mana cost, causing you to get infinite cascade triggers based off the mana value of that spell.