As soon as you pull the lever the team will be split into different rooms. You will be grouped based on who you are lined up with in the horizonal rows of the lever tiles. So make sure you are standing in line with an appropriate team for the first phase.
Phase 1
The first phase involves killing a Fallen Challenger with your group. This is a straight forward kill and when it dies it will leave behind a mystic flame (). Make sure you step into this flame and NOT the teleporter to move to phase 2. When stepping in this flame you will be teleported to the main room and meet up with the rest of the team. Make sure not to stand still as you enter the flame or you could get trapped by the dragons in the room. You may want to time it with others so you aren't the first one in the room depending on your level/vocation.
Phase 2
Now that you have entered the main room you will find a few things:
- Unbeatable Dragons - these will take no damage
- Dragon Wardens - these can be killed but will continuously spawn
- Spirit of Fertility - will have to be protected and lured across the room
A knight should challenge the 5 unbeatable dragons and lure them to the North or South of the room. It is everyone else's job to lure the Spirit of Fertility from the right side of the room where it spawns (the water area) to the left side of the room where you can find the Dry Flower () (grass area).
When you lure the Spirit of Fertility onto the Dry Flower it will turn into an Angry Plant (). Kill this Angry Plant and it will leave a Flower Bowl () on the ground. If you have a second knight they should challenge one of the Unbeatable Dragons and lure it onto the Flower Bowl. When an Unbeatable Dragon steps onto the Flower Bowl it will turn into a Somewhat Beatable Dragon (). The team should attack and kill this Somewhat beatable Dragon which should die quickly. You must repeat this process until all of the Unbeatable Dragons have been killed. Note: Creatures can damage the Spirit of Fertility and Druids can heal it with Mass Healing.
Phase 3
Once the last Somewhat Beatable Dragon has been killed 6 Dragon Essence () will spawn. These can hit quite hard (upwards of 2000 damage each) and share a health pool. If your blockers are strong enough you can group them all together and attack with AoE. If not just focus with single target to bring them down.
Phase 4
Once the Dragon Essence are killed The First Dragon () will spawn. This boss isn't too difficult at this point. It just has a lot of health. The team will have to focus all of its firepower. The boss can be trapped to make the aiming of spells easier but periodically throughout the fight it will teleport to somewhere else in the room. If you are a mage you may want to mana shield or a lower level paladin be careful with your sharpshooting in case the boss teleports right next to you. Once The First Dragon is killed you will be immediately teleported to the reward room.
If you want to see a video of the whole boss you can find an example of me killing it here:
https://www.youtube.com/watch?v=akUxT5o7mMA