Tanks and healers both need to be aware of this mob's Gravity Strike ability. It cannot be blocked, dodged, or parried and drops the target's health by 60%.
What can be interrupted is the powerful Shadow Strike ability. It has a 3-second cast time, but if successful, will inflict a massive amount of damage to the target. The Strike incorporates a [Shadowstep]-like mechanism to move behind the target to deliver the blow.
For those wishing to stealth through sections of the Caverns, be aware the Zealots can sense players.