Found in the Convergence Wing of the dungeon, the Exarchs will require a diverse group and considerable guile to defeat them. At time of writing only 4 of these have been encountered.
Riftborn Monstrosity
Found in the Skara Brae town instance this revolting creature spawns mawlings
Gnarled Veilkeeper
Found in the Minoc town instance, this sentient tree creates highly damaging brambles at the feet of nearby mobiles and creates clones which, if not killed in time, will turn into an evil twin. Absorbing fire damage he will begin to combust repeatedly, dealing significant AOE damage to himself and nearby mobiles.
Vor’lthar the Void Maw
Found in the Yew town instance this meat ball has two phases of being. In phase one devours and spits out nearby mobiles doing damage in the process. Reducing the creatures health to zero triggers phase two, and restores his full health. Now using mage abilities he applies a gaze debuff to nearby players and shoots energy bombs at them. Move before the bomb explodes.
Riftbreaker Construct
Occupying Jhelom town instance this electifying golem sets a timed energy bomb on nearby mobiles. Unlike the Blizzard elemental where it is crucial to keep moving while under the effect, in this instant it is vital that players be stationary when the timer expires. The bomb will explode and send a blue energy shockwave in a circle around you. If moving you will encounter more of the shockwave, which is then usually fatal. Running into the shockwaves of other players is also usually fatal. He explodes upon death killing anyone in range.