I loaded up with around 15 scrolls of meteor shower for 2 of my party members and let loose but it still took a long time to beat the dragon down.
For my next try I found a way to cheese the dragon using waidwen.
When a party member steps on waidwen’s symbol of eothas, they get a buff AND waidwen unleashes the godhammer on the dragon. This attack does around 500 damage and has infinite range so it can hit the dragon anywhere in the arena.
Before the triggering the cutscene and conversation you need to keep most of your party back and near the jump point to waidwen. Then have som