The Dragon (or Drake in other languages) can be found in Skyrock as a Raid Boss in the bottom left, and requires a minimum of Level 20, an Icy Vein scroll in your inventory, and 5 players.
Once in the room, everyone needs to proceed to the top and the fight will start. The dragon may trigger before this, but it will fly away and come back once everyone has gathered. The fight lasts for 5 minutes, at which point you need to deal enough damage to drain its health bar.
The dragon has multiple attack patterns, and most of its damaging moves can be detected with the red damage cone/circle that appears for the attacks. The only attacks that do not show these areas are the breath attacks up close, which most players can live through.
After a period of time, the dragon will fly away and shoot down fireballs, which are easily avoided, and the attacks will resume once the dragon lands. Having an Archer and Wizard in the party will help even the odds, as their skills will give regen for health and mana accordingly. Fighting at range is helpful, but not required, as long as you can dodge the attacks quickly.
Use the Dragon scrolls to keep up the 400% damage modifier, keep your health above half, and hope your team can stay alive to win. My team ended up with literally 1s left on the health bar with 3 people remaining in the fight, so don't waste your time if your team has dropped out.
I hope this helps. The hard part is just getting the fight started with 5 players.