Heroic Stonecore Boss Guide

There is an updated version of this guide available and it includes videos of the boss fights.
Go here to see it: The Stonecore - Heroic Boss Guide

Corborus:

Stay out of pink/purple shards. They explode and deal huge AoE and place a debuff on you that increases your damage taken. AoE the shards down. When the boss burrows, stay away from dust clouds. The boss will do a dolphin dive and one shot you. Kill rock elementals that spawn.

Slabhide:

Avoid dark shadows on the floor. Spikes will fall down from above and one shot you. Stay away from dust clouds, they spawn lava pools. When he casts Crystal Barrage LOS behind a spike that is out of his hit box.

Ozruk:

Casts Ground Slam which is a cone of spikes. One shots tank. Walk through his model when he casts it to avoid it. You can also choose to sidestep it. Casts Elementium Spike Shield. Whenever you melee him, you place a DoT on yourself. You want this. Also casts Elementium Bulwark. This reflects spells. This is spellstealable but only do so if your healer/ranged are far enough form the boss (20 - 30 yards). Casts Paralysis - Shatter combo. One shots everyone in range. He will cast Paralysis and the only way to break it is through dispel Magic or damage done to you. This is where the DoT comes in for melee. As soon as your Paralysis is broken run away from him.

High Priestess Azil:

Casts Gravity Well. Stay out of it. Summons adds. Hide behind the Gravity Wells so that the adds have to run through them, thus killing them. When she is on her pedestal she will throw boulders at you. Stay away from dust clouds. More adds will spawn. Kill boss.