Nibelheim Aflame

If the target creature is an illegal target as Nibelheim Aflame tries to resolve, it won't resolve and none of its effects will happen. No damage will be dealt, and you won't discard and draw even if you cast Nibelheim Aflame from a graveyard.

A spell cast using flashback will always be exiled afterward, whether it resolves, is countered, or leaves the stack in some other way.

"Flashback [cost]" means "You may cast this card from your graveyard if the resulting spell is an instant or sorcery spell by paying [cost] rather than paying its mana cost" and "If the flashback cost was paid, exile this card instead of putting it anywhere else any time it would leave the stack."

You must still follow any timing restrictions and permissions, including those based on the card's type. For instance, you can cast a sorcery using flashback only when you could normally cast a sorcery.

You can cast a spell using flashback even if it was somehow put into your graveyard without having been cast.

Use the power of the target creature as Nibelheim Aflame resolves to determine how much damage it deals to each other creature.