The actor, who plays Bobby Singer, suggested in a recent Twitter post that the final two episodes of the show's sixth run will "blow [viewer's] minds".
"Between [showrunner] Sera Gamble's penultimate script and [series creator] Eric Kripke's script for the season finale, [Supernatural] is going to blow minds," he wrote. "Didn't see this coming."
He also insisted that there is still no official word on a possible seventh season of the CW drama.
"Everybody who works on [Supernatural] is ready and willing to do a seventh season," he explained. "We just don't know yet. Waiting on the CW to decide."
Beaver previously claimed that he has "no reason to doubt" the show's renewal.
Supernatural will return to The CW on April 15.