In order to regain power by absorbing their blood, Shilen initiated the sacrifice of creatures inside Catacombs and Necropolises across Aden, leaving behind a deathly aura. King Amadeo ordered that the entrances to all Catacombs and Necropolises be shut, to keep adventurers out and to keep the deadly auras in. When these dungeons were shut down, the Seven Signs quest cycle ground to a halt and the following changes were made:

• The effects of the Seals of Avarice, Gnosis, and Strife no longer apply.
• The maximum tax rate of the castle is fixed at 15%.
• Elite mercenaries can no longer be hired or posted with Seals of Strife.
• The siege function management cost is no longer affected by Seals.
• Characters can no longer enter the Festival of Darkness and the Dimensional Rift instances.
• The Anakim and Lilith raids are no longer available.
• Scrolls of Ancient Magic that could be obtained from Catacombs and Necropolis are now dropped by monsters in hunting fields.
• The Blacksmith of Mammon and Merchants of Mammon now move randomly among the 11 villages.
• The responsibilities and functions of Dusk Priestess and Priest of Dawn NPCs have been taken over by the Priest of Mammon, who offers different items for sale for Ancient Adena.
• Functions that required Ancient Adena can now be carried out with regular Adena.
• Red/Blue/Green Seal Stones currently in a character's possession can be exchanged for Ancient Adena with the Priest of Mammon.

Source: Lineage2.com