Has several mistbound vindicator adds that share some of the abilities. You can mow these down with AoE spells.
The Elemental Warder uses the same Invalidation ability that others in the zone use. It's a giant mit/stat debuff that needs to be cured immediately or your tank will probably get one-shotted.
Curse of Insanity for this mob is a Nuke and will go off when you go below 50% power. Anti AOE abilities on the pull will help with this attack for atleast 4 minutes until he casts it again. If you have an incurable elemental on you, that is Curse. If you go below 50% power each spell cast you do has a chance to activate it and your "brain will explode".