Reign of the Fallen by Sarah Glenn Marsh

Odessa is one of Karthia's master necromancers, catering to the kingdom's ruling Dead. Whenever a noble dies, it's Odessa's job to raise them by retrieving their souls from a dreamy and dangerous shadow world called the Deadlands. But there is a cost to being raised--the Dead must remain shrouded, or risk transforming into zombie-like monsters known as Shades. If even a hint of flesh is exposed, the grotesque transformation will begin. A dramatic uptick in Shade attacks raises suspicions and fears among Odessa's necromancer community. Soon a crushing loss of one of their own reveals a disturbing conspiracy: someone is intentionally creating Shades by tearing shrouds from the Dead--and training them to attack. Odessa is faced with a terrifying question: What if her necromancer's magic is the weapon that brings Karthia to its knees?

Criminal prodigy Kaz Brekker has been offered wealth beyond his wildest dreams. But to claim it, he'll have to pull off a seemingly impossible heist:

Break into the notorious Ice Court (a military stronghold that has never been breached)

Retrieve a hostage (who could unleash magical havoc on the world)

Survive long enough to collect his reward (and spend it)

Kaz needs a crew desperate enough to take on this suicide mission and dangerous enough to get the job done - and he knows exactly who: six of the deadliest outcasts the city has to offer. Together, they just might be unstoppable - if they don't kill each other first. 

Sixteen-year-old Lara Jean Song keeps her love letters in a hatbox her mother gave her. They aren’t love letters that anyone else wrote for her; these are ones she’s written. One for every boy she’s ever loved—five in all. When she writes, she pours out her heart and soul and says all the things she would never say in real life, because her letters are for her eyes only. Until the day her secret letters are mailed, and suddenly, Lara Jean’s love life goes from imaginary to out of control.

Brooklyn Stevens sits in a pool of her own blood, tied up and gagged. No one outside of these dank basement walls knows she’s here. No one can hear her scream. Sofia Flores knows she shouldn’t have gotten involved. When she befriended Riley, Grace, and Alexis on her first day at school, she admired them, with their perfect hair and their good-girl ways. They said they wanted to save Brooklyn. They wanted to help her. Sofia didn’t realize they believed Brooklyn was possessed. Now, Riley and the girls are performing an exorcism on Brooklyn—but their idea of an exorcism is closer to torture than salvation. All Sofia wants is to get out of this house. But there is no way out. Sofia can’t go against the other girls...unless she wants to be next.

Children have always disappeared under the right conditions; slipping through the shadows under a bed or at the back of a wardrobe, tumbling down rabbit holes and into old wells, and emerging somewhere... else. But magical lands have little need for used-up miracle children.

Nancy tumbled once, but now she’s back. The things she’s experienced... they change a person. The children under Miss West’s care understand all too well. And each of them is seeking a way back to their own fantasy world. But Nancy’s arrival marks a change at the Home. There’s a darkness just around each corner, and when tragedy strikes, it’s up to Nancy and her new-found schoolmates to get to the heart of the matter. No matter the cost.