Torrential Gearhulk
Oracle Text
Flash
When Torrential Gearhulk enters the battlefield, you may cast target instant card from your graveyard without paying its mana cost. If that card would be put into your graveyard this turn, exile it instead.
Card Rulings
9/20/2016 If you cast the card, you do so as part of the resolution of Torrential Gearhulk’s triggered ability. You can’t wait to cast it later in the turn. Timing restrictions (such as “Cast [this card] only during combat”) still apply.
9/20/2016 If you cast a card “without paying its mana cost,” you can’t choose to cast it for any alternative costs, such as emerge costs. You can, however, pay additional costs. If the card has any mandatory additional costs, such as that of Incendiary Sabotage, you must pay those to cast the card.
9/20/2016 If the card has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
Edit I didn't see that ts exiled itself. Rip. I can ts (card)pull from eternity(/card) then ts again with the hulk I guess. Damn son I even use that stupid sundial, which exiles its own ability off the stack as part of the resolution. Why did I think it was different?
Those don't work either though, since this is Instant-only.