Argul's Tome of Necromancy

Exchange your life force for power, taking 2d8 damage, causing blood to deep scratches to appear on your body, launching with blood that merges itself into Argul's Tome of Necromancy, lasting for 1 minute.

While the tome is active, all necromancy spells deal an extra 1d6 necrotic damage, 2d6 if the spell casted is a spell of Argul.
At higher levels; The damage of this item increases by an additional 1d6/2d6 per spell slot higher than 2nd.