From Emil Chronicle Wiki

Arcana Diamond is a level 38 monster.

[edit] Stats

Basic	Combat
Level 38 Experience 380 Job Experience 320 HP 580 SP 110 MP 255 Behavior  ???	Type Magic Creature A.SPD 2.10 ATK 115 - 145 DEF 160 C.SPD 2.10 M.ATK 80 - 88 M.DEF 185
Properties Earth(30%) Item Drops Paper, Stamina Potion, Ancient Book, Old Book, Arcana Diamond Stamp Skills  ??? Location Northern Dungeon