The Walking Dead | [s4e22]

Bonnie uses an "Expression triangle"—fueled by the deaths of 12 hybrids, 12 humans, and 12 witches—to drop the veil between the living and the dead. This allows ghosts to temporarily manifest in Mystic Falls. Reunions and Revenge:

The original vampire Kol returns seeking revenge on Elena and Bonnie.

Stefan’s best friend Lexi returns, providing emotional support and suggesting that his romantic chapter with Elena is truly over. [S4E22] The Walking Dead

Bonnie Bennett attempts to drop the "veil" to the Other Side to communicate with Qetsiyah and find a way to defeat Silas.

Elena visits Jeremy’s grave, hoping the veil being down will bring him back. Bonnie uses an "Expression triangle"—fueled by the deaths

Elena Gilbert, still struggling with her humanity and grief over Jeremy’s death, seeks revenge against Katherine Pierce. Key Plot Developments

Silas uses his psychic powers to torment the group, specifically making Caroline hallucinate that she is cutting herself. Bonnie eventually uses Expression to turn Silas’s body into stone, though he remains a threat if he receives even a drop of blood. Character Arcs Elena Gilbert, still struggling with her humanity and

To save her friends, Bonnie takes on the immense strain of channeling dark mystical energy, a move that sets the stage for the season finale's consequences. 'The Vampire Diaries' Recap: 'The Walking Dead' - WSJ