Nina Dobrev and Paul Wesley

With three episodes left and a full moon rising, The Vampire Diaries prepares to close its sophomore season by upping the stakes. Thursday's episode of the CW drama (at 8/7c) — titled "The Last Day" — is the precursor to the long-awaited ritual that may create a new race of vampire-werewolf hybrids, if Klaus (Joseph Morgan) is able to scrounge up the materials needed. And boy, will he stop at nothing to do so.

Check out six reasons why this week's episode should not be missed: 

Exclusive Vampire Diaries first look: The season finale is on fire!

6. The Gilbert ring will not save Elena: Since the doppelganger is a supernatural being, the Gilbert ring, which kept Jeremy (Steven R. McQueen) from dying when Damon (Ian Somerhalder) snapped his neck, will not work on Elena (Nina Dobrev). Though Elijah (Daniel Gillies) may be able to keep her alive, Damon doesn't trust him and will decide to take matters into his own hands.

5. Klaus needs to hunt down his ritual shopping list items: The ritual, as we've heard before, needs a witch, a vampire, a doppelganger and a werewolf. Conveniently, the ritual coincides with the return of Tyler (Michael Trevino) to Mystic Falls. Even if you think you know who will fill each of those positions, you're wrong — dead wrong.

4. There are reunions galore: The real Alaric (Matt Davis) returns! And though Jenna (Sara Canning) has been freaked-out by the news that vampires are real, their reunion is sweet. Tyler and Caroline (Candice Accola) ... not so much, especially once put in a compromising position.

Vampire Diaries Star: If Katherine was 10 steps ahead of everyone, then Klaus is on the moon!

3. Matt's cracking under the pressure: Acting as though you don't know your girlfriend is a vampire is one tough feat, and Matt (Zach Roerig) is beginning to crumble as he questions whether there is still humanity inside Caroline and if he can love her even though she's undead.

2. Elena will be faced with her mortality: With the full moon ritual upon them, Stefan (Paul Wesley) decides to show Elena what she'll miss if she dies. However, she'll make a declaration so unexpected that, executive producer Julie Plec says, it will set the series apart from Twilight once and for all.

1. Two moments will change the series forever: Sometimes producers exaggerate when they say something is a "game changer." In this case, there is one moment that will make you question how this series can go on, and another that will break your heart.