The Sentinel of Earth  

"Grouped" with The Sentinel of Stone

When you first get to the room with the two Sentinel's in it, you will also see 4 heroic mobs, two at the base of each Sentinel. None of the mobs are grouped, however, everything will come at the same time.

To start, have the tank run in and pull a mob. This will cause both Sentinel's to come alive, as well as the 4 unlinked mobs to attack. Run back into the tunnel and the Sentinel's will leash, letting you kill the Heroics with ease.

When you are ready to take on the named, they are pretty easy. They do do a knockback and have frontal AoE. You want to tank them close to where they stand as pulling too far out will cause them to leash and reset.