Requires

Steps

1. Cast the additional instant or sorcery by paying its mana cost.
2. If Adaptive Training Post had two charge counters on it, it triggers, putting a charge counter on it.
3. Holding priority, activate Adaptive Training Post by removing three charge counters from it, copying the next instant or sorcery spell you cast this turn.
4. Cast Twincast by paying its mana cost, targeting the spell cast in step 1.
5. Adaptive Training Post triggers, copying Twincast, with the copy targeting the original Twincast.
6. Resolve the copy of Twincast, copying the original Twincast, with the copy targeting the original Twincast.
7. Repeat step 5.

Results