Helgaia will go into an 'Stagger-check' Lost Ark Gold that you have to break. The boss folds its wings in front of itself. Keep Stagger talents for the moment.
Helgaia is counter-active. charge . Watch for the moment that your boss becomes blue. Hit your counter skill with precision to stagger the boss for just a brief period. The charge will be enhanced (the boss takes flight) If you let Helgaia to grow.
There are three phases of attacks. During the phase 1 you can choose to Charge, an Fling attack (will take you up in the air) A Tail Whip (watch out when you are back-attacking), a Wing Attack, and a Leap Attack.
In Phase 2, Herlgaia's attacks are improved - the Charge is improved so that Helgaia is able to fly when she is charging and the Fireball attack has now three shots.
Phase 3 includes Meteor Rain - check cheap Lost Ark Gold the image below. The area of impact is marked by a bright yellow area. Be careful not to stand on that spot. You could be hit by more than one meteor, causing a sort of"juggle" effect, which basically takes you from the fight for a short time.