Book of Underworld
From JUMP: Assemble Wiki
Book of Underworld is a Tier 2 Magic 
Equipment.
Book of Underworld Reduces enemies' HP regen.
In order to obtain Book of Underworld you will need:
| Magic Attack | 190 |
| Max Mana | 500 |
| Movement Speed | 5 |
| Cumulative Price | 2570 |
Sole Passive - Poison: After hitting an enemy target with a skill, reduces their healing efficiency by 50% for 3s.