Halls of Lightning
Last night we did the Heroic dungeon instance: Halls of Lightning.
Here is a screenshot of us fighting the 4th and final boss Loken.

This boss has three attacks to watch out for:
Pulsing Shockwave: Inflicts Nature damage to each player every 2 seconds over the course of the fight. Damage depends on the distance to Loken.
Arc Lightning: Inflicts Nature damage to a random player. Has a chance to jump over to a nearby player.
Lightning Nova: Inflicts Nature damage to all players within 20 yards range. Cast time 5 seconds.
All in all a fun night, ran a few heroic dungeon instances and called it a night as usual.