Phantasma by Kaylie Smith

Caraval meets Throne of the Fallen in this spicy dark romantasy where a necromancer needs help from a dangerous phantom to win a deadly competition, only to find their partnership puts her at risk of breaking the game’s most vital rule: don't fall in love.

When Ophelia and her sister discovers their mother brutally murdered, there is no time to grieve: Ophelia has inherited both her powerful death-driven magic and enormous debt on their home. Circumstances go from dire to deadly, however, when Ophelia’s sister decides to pay off the loan by entering Phantasma—a competition where most contestants don’t make it out alive and the winner is granted a single wish.

The only way to save her sister is to compete. But Phantasma is a cursed manor, with twisting corridors and lavish ballrooms, and filled with enticing demons and fatal temptations. Ophelia will need to face nine floors of challenges to win... if her fears don’t overtake her first.

When a charming, arrogant stranger claims he can protect and guide Ophelia, she knows she shouldn’t trust him. While Blackwell may not seem dangerous, appearances can be deceptive. But with her sister’s life on the line, Ophelia can’t afford to turn him away. She just needs to ignore the overwhelming, dark attraction drawing them closer and closer together.

Because in Phantasma, the only thing deadlier than losing the game is losing your heart.