Requires

Twincast must be in hand. Fork must be in hand. You have a way to cast an additional instant or sorcery, or an opponent is casting one. Mana needed: , plus enough mana to cast the additional spell if needed

Steps

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

Results