Passive: Morde Passive (The DoT AoE would hopefully work with Taric's W for two death fields)
Q: Kai'Sa Q (What's scarier than one Icathian Rain? two Icathian Rains with a support's CDR)
W: Taric W (As can be seen from all the other stuff)
E: Annie's E (Would affect the support and linked ally, damage resist and free AP scaling thornmail, anybody?)
R: Janna Ult (Only the support would likely need to channel, acts as peel and healing)
Here we'd have an enchanter who, in laning phase would be slightly underwhelming in terms of healing, while still having good zoning potential for their ADC. And come late game this would be the most faceroll-y champion imaginable, just W+E+Q the carry and then ult if things get hairy. Plus everything but the Taric W is AP scaling (or partially AP scaling, in the case of the Q), so the champion has an easy build path of hard battlemage stuff after their support item