u/large_herbivore

Let's say my opponent has a Quirion Dryad in play and I want to try to kill it with Lava Dart. So, in response to my opponent casting a non-green spell, I cast Lava Dart. But oh no! They have another non-green spell to cast in response to that. Can I then flashback Lava Dart, even though the original cast hasn't finished resolving?

I think the core rules concept I need to understand to answer this question is what happens to an instant (or any nonpermenant spell) once it's cast. Does it immediately go to the graveyard (and therefore become available to flashback) or is it "somewhere else" until it finishing resolving?

Thanks!