From Emil Chronicle Wiki

Black Ghost Spider is a level 49 monster.

[edit] Stats

Basic	Combat
Level 49 Experience 3,400 Job Experience 5,400 HP 14,500 SP 200 MP 250 Behavior  ???	Type Insect Boss Skill A.SPD 3.00 ATK 80 - 130 DEF 200 C.SPD 1.50 M.ATK 110 - 120 M.DEF 85
Properties Earth(50%) Item Drops Thread of Seduction, Black Knee-High Socks Skills  ??? Location Some Instance Dungeon