One thing I'd like to note, by the way (after reading through several pages of this thread after posting my own reply), Karma is far from squishy. In fact, she's one of the hardest champions to kill in the game, after you take into consideration her E and Q (plus baiting Darius/Garen ults is delicious). Yes, she's got short range, but she also has natural tankiness (in terms of sheer HP) that other supports like Janna, Lulu and Soraka don't have.
Originally Posted by RiotAmes
3b) If making an AP, have enough spells that combine in a clear or meaningful way to keep the gameplay interesting.
To be fair, their are champions like Sion and Twisted Fate who effectively have two abilities, too. The bigger problem with Karma is that her damage relies on using Mantra (for Soul Shield, which means one less Mantra for a heal from Heavenly Wave), or a completely unintuitive, moving, tethered, line skill shot (Spirit Bond).
I'd also like to say that her Q not healing as much as Soraka's or Taric's is fine, given that, like Alistar's heal, it can heal minions (and/or multiple champions) and has the potential to keep a lane pushed or freeze a lane. But even then, it just doesn't heal enough
to mean anything in the long run (one extra turret hit on a minion, if you're lucky). Besides, the conal aspect of it makes it impossible to heal all of your allies if you and your allies are not in perfect positioning - warranting a possible buff to the heal itself. I'd be hesistant to touch the AP ratio on the heal, as it would possibly make AP Karma even more underwhelming to nerf it, but it would make it feel like you have to go AP Karma if you buff it.