Cursed Tome is an event encountered in the 2nd Act of Slay the Spire.
Event progress 
Edit
"In an abandoned temple, you find a giant book, open, riddled with cryptic writings. As you try to interpret the elaborate script, it begins to shift and morph into writing you are familiar with."
[Read]
[Leave]
When reading:
"Odd. The book seems to be about an Ancient named Neow.
This piques your interest, but you have a general feeling of malaise."
[Continue] Lose 1 HP.
"The Ancient of resurrection, Neow, was exiled to the bottom of the Spire.
You feel compelled to read more, but your body begins to ache."
[Continue] Lose 2 HP.
"Seeking vengeance, Neow blesses outsiders, using them for her own purposes.
You are starting feel very weak and tired."
[Continue] Lose 3 HP.
"Those resurrected by Neow remember only fragments of their past selves, cursed to fight for eternity.
As you near the final page, your old wounds begin to reopen!"
[Take] Obtain the Book. Lose 10 HP (Ascension 15: Lose 15 HP).
[Stop] Lose 3 HP.
