The title card for Supernatural season 15 might provide a hint as to how Sam and Dean Winchester defeat this season's arch nemesis, God Almighty himself. Returning for its final season, Supernatural jumped right back into the paranormal action, as Sam, Dean and Castiel fought back against the raft of souls emanating forth from Hell's open gateway. This allowed for the return of some classic monsters from Supernatural's very first season, but once the Winchesters finally had time to stop and catch their breath, attention turned to the cause of the apocalyptic situation - God. While Sam optimistically speculated that God had "gone," the brothers aren't likely to get off so lightly and will have to throw down with Chuck sooner or later.

One of Supernatural's longest standing traditions is that the title cards are redesigned each season and generally reflect the story arc of that particular run. For example, season 4's card featured a smattering of angel wings, heralding the arrival of Misha Collins as Castiel in the season premiere. Season 7's card burst into black blood, mirroring the Leviathans that acted as that season's main villains. And Supernatural season 13 featured a golden eye, hinting towards the appearance of Jack, a nephilim whose eyes turn gold when powering up.

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Understandably then, anticipation was high for Supernatural's final ever title card and the end result didn't disappoint. The season 15 card is a montage of different features. Several symbols from Supernatural's history can be spotted, likely as simple Easter eggs that pay homage to the show's history, and there's an undertow of lava that might represent the opening to hell Sam and Dean are currently seeking to shut. The bulk of the title card, however, is dominated by a dark, flowing substance that seems to reach out towards the screen and bears a striking resemblance to the cosmic entity that resides in the Empty.

Supernatural Empty Shadow

Introduced in Supernatural season 13, the Empty is the place angels go when they die, and is presided over by a powerful, mysterious flowing blackness. After God broke bad in the season 14 finale, Billie was seen in the Empty recruiting Jack for an unspecified job - and the Entity is right there with her, smiling. Clearly, this strange shadow has a key role to play in whatever Billie has up her cloak sleeve. One popular fan theory suggests that Billie is assembling a crack team of powerful beings to help the Winchesters in their final battle against God. If this proves to be true (and it is certainly the most logical explanation), then the prominence of the Empty in the title card implies how important the creature might be.

The shadow of the Empty could be the one to strike the final blow that defeats God. In Supernatural season 14, it was stated that not even God had power over the Empty, while the Entity appears capable of absolute dominance within its own realm, even keeping deceased archangels at bay. Does this revelation, combined with the season 15 title card, suggest that Billie's plan is to have the Winchesters somehow lure God into the Empty, knowing that he would then be susceptible to attack from the shadow?

Viewers have yet to see exactly how powerful the Shadow of the Empty is, but it's certainly a fearsome creation. As master of an angelic graveyard, the Shadow is able to chase down and possess regular angels with ease, and even Jack's nephilim abilities don't seem to scare it. Perhaps, under the right conditions, the Empty's shadow is the only being capable of besting God, and this is why it features so heavily on Supernatural's new title card. Of course, the meaning of Supernatural's season 15 title card is open to interpretation, and where some see the Empty, others may see Sam's bullet wound or a portal to another world. Only time will tell how important the mischievous black shadow will be.

More: Supernatural Season 15 Cast & Character Guide

Supernatural season 15 continues with "Raising Hell" October 17th on The CW.