I'm surprised no one's mentioned this before so I'll have a go at it.
Chilko, really glad to hear that you guys are considering a pure support conjurer, IMO this is the way to go. HOWEVER, before you go and implement this,
you must fix the formula that decides how much XP a support conjurer gets in a grind party!!!
Not only that, but you must fix how necro is burnt as it takes a support conjurer ages to burn off even just 1%.
If you don't fix the XP formula for conjurers and you implement this change, anyone choosing pure support will quickly realize their mistake and depending on how you implement it, either reskill back to warjur or quit the game because they can't reskill away from support.
Again, I really love the idea you have here, please continue to involve the community in the creation of new skills for the support Conjurer.
[Edit]
Ah, eggy mentioned it. I'll leave this as a reinforcement post. +1 eggy