Mage mana sustain items, how about this
What if we take 
as core item for all mages since every mage need mana sustain:
#New Item A
* Recipe: + 
+ 215 (=1200)
* **Builds into: **
* New Item A + 
= New Item B or 
* New Item A + = New Item C
Chalice of Harmony
* **Recipe:**  +  + 300 (=1300)
* **Builds into: **
*  +  = 
*  +  = New Item D
#
Tear of the Goddess
* Recipe: + 
+ 200 (=1000)
* Builds into:
* + 
= 
Since becomes pretty expensive it might not be really suitable for a support part anymore and different to not overload the cdr. That's why I thought about this that would give better acces to the option:
+ + 450 = 
(=2500)
+ 350 (=2800)