Requires

Twincast must be in hand. Reverberate must be in hand. Mana needed:

Steps

1. Cast any instant or sorcery spell, or wait for an opponent to cast one.
2. Holding priority, cast Reverberate by paying , targeting that spell.
3. Cast Twincast by paying , copying Reverberate, with the copy targeting Reverberate.
4. Resolve the copy of Reverberate, copying the original Reverberate, with the copy targeting the original Reverberate.
5. Repeat step 4.

Results