Requires

Spelljack must be in hand. Bonus Round must be in hand. You have an additional instant card in hand. Mana needed: plus enough mana to cast the additional instant card

Steps

1. Cast Bonus Round by paying , causing you to copy any instant and/or sorcery spell you cast this turn.
2. Cast any other instant card from your hand by paying its mana cost.
3. Bonus Round triggers, copying the instant.
4. Holding priority, cast Spelljack by paying , targeting the instant.
5. Bonus Round triggers, creating a copy of Spelljack that is targeting the original Spelljack.
6. Resolve the copy of Spelljack, countering the original Spelljack and exiling it with the ability to cast it for free from exile.
7. Cast Spelljack from exile without paying its mana cost, targeting the instant cast in step 1.
8. Repeat from step 5.

Results