When can I destroy Conjure the Lost to heal Gravehold, and can it still return to hand if destroyed via another spell?

Question

Accepted Answer

Only when you cast it, since destroying it is an optional cast effect. If it is destroyed while cast through something like Vortex Gauntlet, it leaves the game and cannot be returned to hand afterwards.

Aeon's End: War Eternal

When can I destroy Conjure the Lost to heal Gravehold, and can it still return to hand if destroyed via another spell?