Currently we know there is a high chance of magic gear drops and the loot-share mechanics will be much different and geared for the mass encounters.
Taken from Im Rubic on the Runescape forums:
Towards the end of the latest Behind the Scenes Video we were told Mod Chris L would talk to us this week about a newly developed a boss known as Vorago. With today's update, we've finally received our first in-game teaser as to what this is.
On World 24, Mod Chris L has been spawning several creatures known as Scopulus. These creatures wonder around for a few minutes and then head to a cave just north of Falador. In this cave you will see a few Agility short-cuts granting you the ability to jump over a few gaps, however, you won't be able to explore the dungeon for long as you'll be kicked out a few seconds later.
We know very little of what this update will bring, but what we do know, is that it exists, and therefore we will always ask questions and speculate about what is to come. So feel free to accept our curiosity and try to decipher what is awaiting us.
Here is a picture of the Scopulus and they look likebaby Vorago:
Here is a picture of as far as I could get: