The Vampire Diaries, Season 5

Damon:
So here's my pitch. In order to keep the other side in place, you need something to anchor the spell, right, something powerful, like an immortal being powerful. Now Amara was obviously a great choice until she downed the cure, so would you consider someone who's dead but stuck on the other side a viable candidate?

Tessa:
An anchor swap?

Damon:
Because I've got a volunteer.

Tessa:
I'd be making a ghost a human toll booth between our side and the other side, giving her the power to interact with our physical world and the supernatural purgatory.

Damon:
So what's the problem?

Tessa:
I need a massive amount of power to do a transfer spell like that.

Damon:
Fine. Name your poison.

Tessa:
I need something to draw on. The moon's not full, I don't think there's a worthy comet for another couple billion years.

Damon:
think hard. I have a girlfriend at home who misses her best friend and a wacky stowaway on suicide watch. It's ridiculous.

Tessa:
Doppelgängers. They're powerful, mystically, naturally recurring.

Damon:
You want Doppelgänger blood? I got Doppelgängers coming out of my ears. How many do you want?