From Lineage 2 Encyclopaedia

Properties

Mass Curse Gloom
Inflicts dark damage near the enemy with 33 Power added to M. Atk. For 30 sec., decreases the enemies' M. Def. by 15% and Attribute Resistance by 5.
Class	Necromancer
Type	debuff
Attribute	-
Recast time	12 s
Cast time	2 s
Cast range	900
Classes with same skill	Necromancer, Soultaker

Skill Upgrade

Lvl. to Learn	Skill Lvl.	Description	MP Consume	HP Consume	SP
58	1	Inflicts dark damage near the enemy with 33 Power added to M. Atk. For 30 sec., decreases the enemies' M. Def. by 15% and Attribute Resistance by 5.	133	0	121
62	2	Inflicts dark damage near the enemy with 36 Power added to M. Atk. For 30 sec., decreases the enemies' M. Def. by 15% and Attribute Resistance by 10.	144	0	200
66	3	Inflicts dark damage near the enemy with 39 Power added to M. Atk. For 30 sec., decreases the enemies' M. Def. by 15% and Attribute Resistance by 15.	153	0	310
70	4	Inflicts dark damage near the enemy with 41 Power added to M. Atk. For 30 sec., decreases the enemies' M. Def. by 15% and Attribute Resistance by 20.	162	0	711
74	5	Inflicts dark damage near the enemy with 44 Power added to M. Atk. For 30 sec., decreases the enemies' M. Def. by 15% and Attribute Resistance by 25.	170	0	1000