last edited by Aaron Patten
@Soly It could also be worthwhile to use with Flash to get back Paradoxical Outcome for only two mana.
@fsecco The natural pairing with this card seems to be Gifts Ungiven (with honorable mention to Cryptic Command, Tsabo's Decree, and Ad Nauseam). Gifts can have synergy with other graveyard interactions that Oath of Druids enables and also with the Torrential Gearhulk itself. Although it can be Tinkered into play and also exiles to Force of Will I have my doubts that it would be better than what is already commonly used with Oath of Druids strategies. This is mainly because it only interacts with instants and doesn't have flying intrinsically.
If your main plan is to recast a card in your graveyard off of an oath activation Eternal Witness and Snapcaster Mage can accomplish similar tasks without ever being stranded in your hand. They still require you to pay the mana cost of the spell of course but playing higher mana spells like Gifts Ungiven creates a whole other set of issues in deck design by its self. If this were played in an oath deck that deck should probably contain several copies of Mana Drain as well.
The more I think about all the different instants this can re-cast the less certain I am about its interaction with Oath of Druids. Its probably worth testing at the very least. I think the biggest hurtles for a deck like this to overcome will be Flusterstorm and Gush token strategies.