An idea that would make Karma feel a lot, lot better to play.

Switch her Mantra'd W from 20% of missing health both ways to (the numbers don't matter) something like 100/200/300 + .2 AP increased by 1.5% per 1% of missing health.

There is no reason a squishy kite mage who relies almost solely on having high amounts of CDR and AP should actually rely on building HP to access her W's power. Building AP doesn't even remotely benefit it (average 500 build AP only adds 5% to the damage) and it pulls a double bind, because having low HP also means that you can't survive long enough to proc both ends.

Please. Mantra W just feels like a noob trap now if you build AP instead of tank.