The boss is rooted. Careful and don't fall off the ledge behind him.
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Valik is rooted and slowable.
The boss will have an emote, after which anyone in line of sight of the boss, other than the main tank, can be teleported down the ramp causing 2 adds to spawn and that toon becomes drunk. There is a little time to move toons out of line of sight once emote occurs. There is a second emote to indicate that he has finished his attempt to teleport players.
For a pet heavy group: Keep everyone out of Line of Sight, debuff, Send in Tank, then send in pets. For non-pet heavy groups, DPS him and be careful for the emote. You can run to zone in and be out of line of sight once the emote occurs. Wait until the second emote and go in to dps him again.