You can find The Oculus dungeon within Borean Tundra.
The coordinates are (27.2,26.0)
At the end of the platform go into the portal to be transported to the 1st boss. Pick a dragon and fly up to the next level.
Ruby Drake – Tank / Emerald Drake – Healer / Amber Drake – DPS.
Look for the purple glowing platforms (one is protecting 2nd boss). Kill all the mobs on the 6 platforms to release the 2nd boss (shown as * on map below).
Now you can fly up to the next platforms above (with the trees) the 3rd boss will teleport 3 times (shown as * on map below) before you can fight him.
Now fly up to the highest platform to fight final boss.
1. Drakos the Interrogator
2. Varos Cloudstrider
3. Mage-Lord Urom
4. Ley-Guardian Eregos
Heroic Differences: Planar Shift summons Planar Anomalies to inflict arcane damage to players, keep away from them.