- "Welcome, pilgrims, to The Church of Jeremiah Valeska. The only place where you faithful pilgrims can become your very best selves."
- —Ecco to the followers.[src]
At some point after No Man's Land, The Church of Jeremiah Valeska is formed and Ecco becomes their leader, working under the orders of Jeremiah. They made their headquarters in the Old Town Church located in an unnamed area of Gotham City that was classified as The Dark Zone.
Looking for Jeremiah, Bruce Wayne and Selina Kyle travel to the Dark Zone and stumble upon the Church during one of their recruiting sessions. Ecco dons her Mummer mask and a red and black robe and preaches to the people who wish to become followers. Bruce and Selina ponder about her identity, as it is concealed by the mask. Several people pledge themselves and Ecco tells them to go up the stairs to perform a task to prove themselves worthy, while she orders the rest of the people present to get out. Selina pledges herself in order to get closer to Jeremiah and Ecco orders her to follow the rest of the followers. As Selina leaves, Ecco whispers to one of her henchman and then proceeds to take off her mask and smile deviously, revealing that her face is now painted like a clown.
Ecco goes to the recruits and explains the rules of the task to them. Each person will get one gun and one bullet. Their task is to fire the gun into the neck of the person in front of them, while the follower behind them does the same. Ecco counts from three, but toys with the followers to ensure they are paying attention. Many of the followers are killed from the shot, while a few of them survive, including Selina who blocked the gun with her claw on her glove. Ecco is upset with Selina and reveals that she had previously performed the task as well, the bullet still remaining inside of her body. Ecco holds the gun to her head and pulls the trigger, laughing maniacally as the gun clicks. Selina tells Ecco that she is insane, but Ecco denies this, saying she allowed herself to look death in the face, which allowed the old her to die. She also reveals that she is fully aware of who Selina is and she and Jeremiah have been keeping tabs on everything to do with Bruce.
Ecco points the gun at Selina but Selina knocks the gun away and the two of them fight until Selina gains the upper hand, holding the gun to Ecco's head, who told her she knew she could do it and that all she needed was a little push. Bruce comes into the room, and calls out to Selina. Ecco taunts Selina, saying that her boyfriend is worried, and says she doesn't think Selina can shoot her. Selina hesitates just long enough for Ecco to knock the gun away, stab Selina in the leg, and flee. Selina catches up with Ecco just as she closes the gate behind her. Ecco mockingly waves to Selina before walking away as Selina growls in frustration.
- Jeremiah Valeska (leader; formerly)
- Ecco † (leader; formerly)
- Selina Kyle (feigned)
- Multiple unnamed followers
- Sykes †
- Unnamed Doctor
- Jervis Tetch (formerly)
- Thomas Wayne imposter † (hypnotized)
- Martha Wayne imposter † (hypnotized)
- Alfred Pennyworth (hypnotized; formerly)
- Hypnotized thugs
- The Joker himself, whom Jeremiah is based on, had a similar following in the Batman: The Animated Series spin-off Batman Beyond, which saw groups known as Jokerz operating in Gotham City decades following the Joker's disappearance (in reality, he was dead). When Joker made his "return" to the city in the feature length film Batman Beyond: Return of the Joker, Joker ended up recruiting some of the Jokerz members to assist him in his schemes.
- The Church of Jeremiah Valeska is similar to the Cult of Jerome, which was led by Jerome Valeska and later taken over by Jeremiah.
- Essentially, Ecco was the one who actually "lead" the cult, while Jeremiah is the one truly in charge.
- The current status of the cult is unknown as their primary reason for existing seemed to be to join the Soothsayers in digging a tunnel into Wayne Manor.