The finale of "Doctor Who" season 9 will be the most explosive one yet. Heartbroken by the absence of his companion Clara, the Doctor heads back to Gallifrey, where he partakes in a larger-than-life battle against other Time Lords all while he reels away from the immortal Ashildr's betrayal.

Showrunner Steven Moffat teased to Radio Times that the finale titled "Hell Bent" will show what happens when the Doctor is extremely "pissed off," something that enemies would not want seeing. As it turns out, the Doctor becomes "a mad bad dangerous bastard" and "a lawless man."

The Time Lord will be in a very bad mood returning to his hometown, that's for sure. Notably, it took him two billion years, a horde of beat-up monsters, a shattering deception and the death of a companion to get there.

"I think we probably take the Doctor right to the very end of his tether," Moffat hinted, adding that the "Doctor Who" season 9 finale is titled that way for a reason that fans will look forward to seeing.

In the breathtaking promo for the upcoming action-packed "Doctor Who" season 9-ender, the Doctor recounts the terrors the Hybrid can do, how it will "destroy a billion hearts" and bring the place he fought so hard to save into annihilation.

Needless to say, he won't let this happen and no matter how many Time Lords stand in his way, the "badass" Doctor, as Moffat described, will not let anyone lay hands of Gallifrey. In turn, the Doctor sets out to singlehandedly defeat anyone and anything that hopes to do harm in his home planet.

In the "Doctor Who" season 9 finale, the Hybrid's face will be fully unveiled and the truth about the baddie will finally come to light. "Hell Bent" wraps up the ninth run of the long-running sci-fi hit on Dec. 5 at 8 p.m. GMT on BBC One and 9 p.m. ET on BBC America.