The Vine Ring
Trigger: Kill all 30 "A Tainted Rock Beast".
Phase One: The 10 "A Bloodthirsty Vegerog" become targettable. Pull and kill all 10 to make the boss mob Derugoak Bloodwalker spawn.
The Boss: Derugoak Bloodwalker uses Meteor Storm. It's a 100 range mana drain, targeted AE. Casters need to do their best at staying max range from MT and Derugoak. Derugoak mem-blurs himself a lot. At about 50% health two vegerog adds will spawn and rush the raid. At about 15% four more vegerog adds will spawn and rush the raid. These adds despawn when Derugoak dies and are mezzable.