Demon Dragon

Either of the Two Gem Walkthroughs will grant you access to the dungeon.

NOTE: It is highly recommended to complete this quest with a party (upon your first entry to the dungeon) or bring a guide with you (a Level 80 Priest or Mage will be best).

Ballista Activation
This quest is taken inside the dungeon.

Activating the ballista will help decrease the HP of Ossus Dragon by 20%. If activated, players just need to deal 80% of damage to defeat it.

After Ryukin evacuated report back to Alex to activate ballista.