Invoke Calamity + Narset's Reversal + Swarm Intelligence

Invoke Calamity

Narset's Reversal

Swarm Intelligence

How it works

1. Cast Invoke Calamity by paying 1.
2. Swarm Intelligence triggers, copying Invoke Calamity.
3. Resolve the Invoke Calamity copy, casting Narset's Reversal without paying its mana cost.
4. Swarm Intelligence triggers, copying Narset's Reversal targeting the original Narset's Reversal.
5. Resolve the copy of Narset's Reversal, copying Narset's Reversal targeting Invoke Calamity and returning the original Narset's Reversal to your hand.
6. Resolve the Narset's Reversal copy, copying Invoke Calamity and returning the original Invoke Calamity to your hand.
7. Resolve the Invoke Calamity copy, casting Invoke Calamity without paying its mana cost.
8. Repeat from step 2.
9. You may also choose to cast any number of instants or sorceries from your hand or graveyard with mana value 4 or less without paying their mana costs during step 3.

This loop is anchored by Swarm Intelligence, whose passive enchantment ability turns every spell you cast into a doubled threat. When you cast Invoke Calamity to pull Narset's Reversal from your hand or graveyard for free, Swarm Intelligence copies the big red spell, which in turn lets you cast Narset's Reversal without paying its mana cost. Narset's Reversal then bounces and copies Invoke Calamity back to your hand, while simultaneously bouncing itself via its own copied iteration. By repeatedly recycling both spells through the stack, you achieve an infinite loop that generates boundless storm count and magecraft triggers, while freely casting any other cheap instant and sorcery spells along the way.