Forge version: Forge 1.16.5 36.1.0
Twilight Forest version: 1.16.5-4.0.426

Death Tome damage ignores armor, which makes them extremely strong for a common mob that spawns in groups inside Lich Towers. They also inflict strong slowness on top of this.

It's magic damage...

Then their damage should be nerfed to 2hp (1 heart) on easy, 3hp (1.5 hearts) on normal, and 4hp (2 hearts) on hard. They are too strong atm for being a random encounter in the 2nd dungeon.